Analysis Feed

May 2021 Weather Recap: Close to Average Temperature & Rainfall Despite Very Chilly & Wet End

 Wet and chilly memorial day weekend

Last May, the month's weather highlight was an Arctic outbreak in the second week of the month that produced the coldest reading in May (34°) since 1891.  May 2021, meanwhile, experienced one of the chilliest ends of any May, as May 28-31 tied May 1884 for the latest four-day streak with lows in the 40s.  This chilly ending was responsible for the coolest three-day Memorial Day weekend on record. 

 

Chart - 3 chilliest memorial day weekends

Despite the month's chilly ending, an extended period of above-average temperatures from May 15-27,  that was six degrees milder than average, kept the month close to average, temperature-wise.  And a very wet May 28-30, in which 2.57" was measured, balanced what, up until then, had been a dry May (these three wet days had as much rain as the previous six weeks).  So, when all was said and done, the month was very close to average on both the temperature and rainfall fronts (-0.3 degrees, and +0.40").

 

Before May's chilly and rainy close, six days in the 10-day period between May 18-27 had highs in the 80s.  This included highs of 89° and 88° during the weekend of 5/22 and 5/23; by contrast, the following weekend had highs of 51° on both days.  This reading (which was eight degrees colder than the average low for these two dates) tied a record for the coolest high on 5/29, and set a new record (by four degrees) on 5/30.

 

Besides the last four days of the month, which were 13 degrees cooler than average, there was an eight-day period from May 5-12 that was five degrees below average.  (However, the chilliest reading of the month, 42°, was on 5/1.)

 

Finally, the last six days of the month all had measurable precipitation, the longest rainy streak since one of eight days in May 2019 (5/10-17).  However, this year's streak had a touch more rainfall (2.68" vs. 2.56").

 

Here are recaps of the previous six Mays:

2020

2019

2018

2017

2016

2015

 

May 2001


April 2021 Weather Recap: Above Average Temperatures, Below Average Rainfall.

 

 Pink blossoms new york city

April 2021 featured ten days with highs of 70° or warmer, the first time April reported this many since 2010, and just the tenth time overall.   (The average number of such days in April is six.)  This above average number of warm days resulted in the month's average high being 2.5 degrees milder than average (its average low was 0.7 degrees above average).  Of the ten Aprils with ten or more highs of 70° or warmer, just four rank among the ten mildest Aprils.  This April ranked 22nd (out of 153). 

 

Chart - aprils with 10+ 70-deg highs
 

The month's  coldest temperature was 28° (on 4/2), which was the coldest reading in April in five years.  And although this April was significantly milder than April 2020 (which was 2.7 degrees colder than average), its coldest temperature was eight degrees colder.  The warmest reading was 85°, which is close to what the warmest reading in April has averaged since 2000 (last April was an exception, with a mildest reading of just 68°).   This reading came five weeks after the year's first reading in the 80s (82° on 3/26), and it was the warmest reading since Sept. 5.  

 

The month's warmest reading was on 4/28, but the most above-average period of the month was the seven days between April 4 and 10, when temperatures were eight degrees above average (high/low of 68°/49°).  In total, the month had twelve days that were five degrees or more above average, and five that were five degrees or more below average.  

 

Another highlight of the month occurred on 4/8 when the humidity dropped to 7% during the afternoon - the second lowest level this century.  Finally, April's rainfall of 2.69" was nearly two inches below average.  All but 0.05" fell between 4/11 and 4/30.

 

Here are April recaps of the past five years:

2020

2019

2018

2017

2016

 Park avenue in the spring


How "Back-Door" Cold Fronts Impact New York's Springtime Weather

 

Back door cold front

 

For the most part, cold fronts move from west to east in the Northeast, but, occasionally, chilly air arrives from the opposite direction.  When it does, this occurrence is known as a "back-door" cold front.   Because such a front's winds usually come in from the ocean, this type of front is often associated with overcast skies (sometimes with drizzle); its east-northeasterly winds bring damp and chilly air. 

These incursions of chilly air that come from the opposite direction occur mostly in the springtime, when their cooling effect is enhanced by the wintertime water temperature of the Atlantic Ocean.  In terms of geographic reach, these fronts mostly impact New York City, the Jersey shore, and New England; only occasionally do they extend as far inland as Philadelphia, Baltimore, or DC.

What follows are 40 instances of the more impressive back-door fronts that have come down from the cold Atlantic.  As you'll read, six of the years had two notable back-door fronts.

 

East to west

June 4, 1895 - Winds shifted from the southwest to northeast during the afternoon, breaking a five-day heat wave (its record highs on June 1, 2 and 3 are still standing).  Between 3PM and 8PM, the temperature dropped from 91° to 64°.  The following day would be overcast, with temperatures stuck in the 60s. 

April 25, 1915 - This date experienced, perhaps, the greatest temperature swings of any in New York's weather history.  After the temperature soared from 47° shortly after midnight to 91° at 3:00 PM, winds shifted to the east-northeast, and the temperature plunged to 52° by midnight.  This was the result of a strong warm front moving through for about ten hours (9 AM-7 PM), then being displaced by a back door cold front.  No rain was produced by the passage of these fronts.  Two days later, a similar scenario unfolded.  After reaching 92° shortly before 4:30 on 4/27, a back-door front moved through a few hours later, and the temperature dropped to 54° by midnight.

April 1, 1917 - In the span of just eight hours, the temperature plummeted from 83° to 44° as a back-door cold front moved through and winds shifted from the southwest to the northeast.  This was the warmest reading of the month, with the next reading in the 80s not occurring for another seven weeks.

March 19, 1918 - After a balmy high of 76° was reached at 3:00 PM (a record for the date that still stands), the wind shifted from the southwest to the northeast, and the temperature dropped like a rock, and was half that reading by midnight.

May 23, 1925 - After the high reached 91°, winds shifted from the southwest to northeast late in the afternoon, and by midnight the temperature had fallen to 59°; the temperature on the afternoon of 5/24 was only in the upper 40s.

July 1, 1933 - After a high in the low 90s, a severe thunderstorm from 8:30-10:30 PM dumped 2.17" of rain.  During the storm the temperature dropped from 88° to 72°, where it stayed for much of the next 24 hours.  And on 7/3, afternoon temperatures got no higher than the mid-60s.  

March 27, 1939 - Today's high/low of 73°/39° followed one of 72°/39° three days earlier.  However, while the low on 3/24 was in the pre-dawn hours, the low today was at midnight after winds shifted to the northeast in the PM hours.  And the following day had temperatures in a narrow range of 35°-40°.

April 25, 1939 - After rising from 53° at 4:00 AM to 86° for a few hours in the early afternoon, winds shifted to the northeast mid-afternoon and the temperature dropped back to 52° by 11:00 PM.  And then three days later the high would be only 46° (20 degrees below average).

July 4, 1941 - Just two days after a torrid high/low of 98°/78°, and winds out of the southwest, today was rainy, foggy and cool, with winds from out of the northeast, and a high/low of just 64°/62°.  Today's high would be July 4th's coolest until 1978.

 

Reverse
  

March 22, 1945 - In the midst of the very mild second half of March, today was an outlier as the high reached only 40° (the low was a seasonable 35°).  Winds were out of the northeast, skies were overcast and light showers fell throughout the day. 

April 13, 1955 - A chilly high of 46° came just two days after a high of 84°.  Skies were overcast and winds were from the northeast.

July 6, 1956 - Although yesterday was cool (high/low of 66°/58°), today was even cooler as the high/low was just 61°/57° under gray skies and winds from out of the northeast.  These two unseasonably cool days followed consecutive days in the 90s.

June 1, 1959 - Today's chilly high of 64°, under mostly overcast skies, followed a five-day warm spell at the end of May that had highs averaging 87°.  Today's conditions were the result of a back-door cold front that moved in from New England last night. 

April 30, 1962 - After three days of summer-like warmth (highs of 91°-89°-80°), and winds from out of the southwest, winds shifted to the northeast after midnight and daytime temperatures were only in the mid-40s. 

April 19, 1964 - The day after the high reached 86°, a "back-door" cold front moved through, and by mid-afternoon the temperature dropped into the mid-50s.  (And on 4/21 the high would be just 44°.)

May 5, 1965 - The day after the high reached 90°, today's was 62°.  Winds came from a north-northeast-easterly direction.

April 28, 1966  - It was a dreary, raw, and damp day, with light rain in the morning.  With a high/low of only 42°/39°, today had the coldest mean temperature of the month.  On 4/26 the mercury dropped from 73° late in the afternoon, to 49° by midnight.  Then the high/low the next two days was 52°/40° and 42°/39°.  Winds were from out of the north-northeast.

April 20, 1972 - The temperature at 4:00 PM was quite chilly, at 43°, a drop of 32 degrees since midnight, and forty-three degrees from yesterday afternoon's 4:00 PM reading of 86°.  This was a result of winds shifting to the northeast from dawn to dusk.

May 24, 1975 - Today's high of 93° (the Saturday of Memorial Day weekend) was the year's first reading in the 90s.  However, the heat was short lived as a cold front from the northeast moved through during the evening, dropping the temperature to 61° by midnight, and into the upper 50s by the following afternoon. 

 

Overcast

Aug. 11, 1979 - The day after a high of 95°, today's temperatures in the afternoon were only in the mid-60s after the wind shifted to the northeast during the morning.  The next day was equally cool (after a chilly AM low of 57°) - and  a wet one, as 1.68" of rain fell; this was on top of 0.87" of rain that fell the night of 8/11. 

March 29, 1985 - This was the third day in a row with exceedingly mild temperatures, and today was the warmest of the three with a high of 82°.  Then a back-door cold front moved through after dark, and by midnight the temperature was down to 55°, on its way to down to 46° by daybreak on the 30th (but still well above average).  

April 19, 1985 - After the temperature soared to 88°, a back-door cold front moved through during the evening, and the temperature was down to 51° the next morning.  Then the cool air retreated on the 21st, and after two more days with highs in the 80s, winds backed around and came from the east late in the afternoon on the 22nd, cooling the temperature down to 53° by midnight.  

March 30, 1989 - After the wind shifted to the northeast, the temperature fell all day, from 76° to 50°; the next day the high/low was 50°/41°, which wasn't far from seasonable, but it was quite a cool-down from 3/29's high of 82°.

March 14, 1990 - One day after Central Park recorded its earliest 80-degree reading on record, the warm front that delivered this extraordinary warmth retreated south of the area, as winds shifted to the northeast, and by afternoon, under a bank of clouds and fog, temperatures tumbled into the mid-40s, forty degrees colder than yesterday. 

May 23-25, 1992 - It was a Jekyl & Hyde Memorial Day weekend.  Saturday had mid-summer conditions, with a high of 92°.  Then a big change came on Sunday as a strong cold front pushed through in early afternoon, and temperatures plummeted from the low 80s to 45° by midnight.  Monday felt more like October, with overcast skies and a high of just 61°. 

April 12, 1996 - The high reached 80°, and then winds shifted to the northeast late in the afternoon, dropping the temperature to 55° by midnight, and 45° by daybreak on the 13th.

May 10, 2000 - After three days with highs in the 90s, winds shifted from the southwest to the east, bringing in much cooler air, and by daybreak today, the temperature was in the mid-50s, where it stayed for the rest of the day.  

June 12, 2000 - One month after a back-door cold front cooled down a hot spell, it was replicated today, with late afternoon temperatures in the upper 50s, and winds coming from the east-northeast 24 hours after temperatures were in the low 90s.

 

Northeasterly winds
 

April 16, 2003 - After peaking at 88°, winds shifted to the northeast and by midnight the temperature was down to 51°.  And on the 17th temperatures slowly fell all day, and it was 36° at midnight.  Winds remained out of the east-northeast for the next six days.

May 14, 2004 - The day after the high reached 86°, the temperature was only in the low 60s in the early afternoon.  However, the wind shifted later in the day and temperatures were back into the mid-80s on 5/15.

April 20, 2006 - Today's high of 83° was the warmest reading of the month.  A back-door cold front moved through during the evening, and by midnight the mercury had fallen to the mid-50s, and the mercury was mostly in the 50s for much of the next day, and stuck in the 40s on 4/22 as a developing nor'easter moved up the coast .

April 29, 2009 - The day after the high reached 90° (and dropped 25 degrees by midnight as winds shifted to the north-northeast), the temperature was in the mid-50s by daybreak.

July 19, 2012 - After yesterday's extreme heat (high of 100°) and humidity, today's high, under mostly overcast skies, was just 76°.  Never before has there been such a drop-off in temperature the day following a reading in the triple digits.  The next day the temperature was around 70° during the afternoon. 

May 28, 2014 - One day after a sultry high of 86°, today was overcast, with afternoon temperatures only in the upper 50s.  The back-door cold front passed through after 10 PM, and the temperature quickly dropped into the low 60s, then gradually falling into the 50s by daybreak, where it stayed for the rest of the day. 

June 1, 2015 - After a week of temperatures in the summery mid-80s today, was 30 degrees colder, with periods of rain, drizzle and fog.  Today's high in the 50s was chillier than any day in May - the first time this has ever occurred.  And tomorrow would have similar conditions. 

May 20, 2017 - An early, three-day heat wave came to an end last night after a shift in wind direction.  Today's afternoon temperatures were in the low 60s, which was about 30° cooler than the highs of  the previous three days.

Nov. 4, 2017 - The day after temperatures were in the mid-70s, the temperature at daybreak today was nearly 30 degrees chillier, the result of a shift in the wind direction; afternoon temperatures were twenty degrees cooler.  On the positive side, skies were mostly clear.

April 8, 2019 - After peaking at 79° at 4 PM, winds shifted from west to northeast, and by midnight the temperature was down to 49°.

October 3, 2019 - The day after the mercury soared to 93° (the first reading in the 90s in October since 1941), winds shifted overnight to a northeasterly direction, and temperatures this afternoon were only in the mid-50s.  Light showers and drizzle fell throughout the day.

 

Overcast Skies_Brooklyn Bridge_RedHanded_StockF

 

 

 

 

 


March 2021 Weather Recap: Mild & Rainy Last Two Weeks

 Daffodils of march

 

The first week-and-a-half of March 2021 was exceedingly dry, with just 0.16" falling thru St. Patrick's Day.  (3/1 was the only day with rain.)  Then, in the last two weeks of the month, regular rainfalls returned, with 3.25" measured (more than 50% above average for that period).  The beginning of the month was also on the cold side, with temperatures four degrees colder than average through the 8th (the coldest day was 3/2, with a high/low of 33°/21°).   The rest of the month was six degrees above average, largely due to the last twelve days of the month, which were nine degrees milder than average (high/low of 64°/45°).  Overall, the month was 3.3 degrees above average, and was the 13th mildest March on record (March 2020 was eighth mildest).   The average high was 4.4 degrees above average; the average low was 2.3 above average.

 

The month's highlight was the record high of 82° on 3/26 – the first reading in the 80s in March since 1998 (and the eighth year in which the first 80+ occurred in March).  Besides this first reading in the 80s, March also had the year’s first readings in the 60s (3/9), and 70s (3/11).  This was just the third year in which all three occurrences happened in March, joining 1945 and 1977.

 

82 degrees

 

For the second year in a row, there was no measurable snow in March, just the second time this has happened; the first time was in 1945 and 1946.  And for just the fifth time, February, which was one of the snowiest, was bookended by a January and March with little snowfall.

 

Chart - snowy february bookended by snow-free months

There were eight days that were ten or more degrees milder than average (including 3/26's high of 82°, which was 29 degrees above average), and two others that were more than ten degrees colder than average.  14 days were five degrees or more above average (including eight in a row, from 3/21-3/28, that were seven or more degrees above average); eight were five degrees or more below average.

 

After back-to-back months with diurnal variations below ten degrees, March's was 16.6 degrees (average is 15.1).  Additionally, the range between the coldest and highest temperatures in March was 61 degrees (21° and 82°), the widest range since 2007, when it was 67 degrees (11° and 78°).  This was in contrast to January and February, both which had variations of only 37 degrees. (The greatest range in March is 72 degrees, which was in 1990, when the temperature extremes were 13° and 85°.) 

 

The month had fifteen days with humidity levels that dropped to 25% or lower at some point in the day (usually in the afternoon), with the lowest being 12% on 3/15 at 4:00 PM (and there were two other days with lowest humidity at 13%).  Finally, ten days had a peak wind gust of 35 mph or higher, with the peak gust at 44 mph, which was clocked during the evening of the 26th (the day with a high of 82°).   

 

Here are March recaps from the five previous years:

2020

2019

2018

2017

2016

 

 March_2021_iphone_calendar-scaled

 

 


Marches of 19th Century Were Far More Wintry Than They Are Today

The_Dakota_1880s

 

Of all the months of the year, March has warmed up the most since the 19th century (1869-1900).  While the average annual temperature so far this century (thru 2020) has been 3.6 degrees warmer than the average annual temperature in the late 19th century, March is 6.3 degrees warmer (April is next, at +5.2 degrees).  In the 19th century, March's average temperature was 36.5°, which would be considered quite cold for March of recent times (and more typical of what February's average is); the last time it was that cold in March was in 1984.  (March 2018 was a cold one by today's standards, with an average temperature of 40.1°). 

 

Eight of the coldest Marches on record are from the 19th century (and 18 of the 25 coldest).  Additionally, 16 current record lows in March are from the 19th century as well as 15 record-low highs.  (One outlier is March 5, 1880, which had a record high that is still in place.)   Five of the six Marches with the the most highs of 32° or colder fell between 1875-1896.

 

Chart - cold cold march of 19th century

Eleven daily snowfall records established in that century still stand today.  The first, third and tenth snowiest Marches occurred in 1896, 1888 and 1890.  But of all of the snowstorms of one foot or more that the City has had, just one was from the 19th century - the Great Blizzard of 1888 that buried the City under 21".  (And for nearly 60 years it was the biggest snowstorm of all time; it's now the City's fourth greatest snowfall).

 

Blizzard of 1888 (2)

 

Ten of the thirty-two Marches had at least one reading in the single digits (for a total of 16).  Since then, just five other years have had it happen.  The last time was in 1967.  The frequency of such frigid March readings dropped from once every three years, to once every generation (24 years). 

 

Here are wintry highlights of the cold Marches of the late 19th century:

March 1, 1869 - High/low of 26°/4°.

March 14, 1870 - This was the fourteenth day in a row with highs of 40° or colder (the average high was 34°); six of the days had highs of 32° or colder.  9.5" of snow fell during this two-week period.  And March 17 was the sixteenth day in a row with lows in the teens or 20s.

March 5, 1872 - This morning's low was 3°, the coldest reading ever experienced in March.  This was the second of three days in a row with lows in the single digits, the most of any March.  This is the third coldest March on record.

March 21, 1872 - High/low of 27°/14° on the first full day of spring. 

March 20, 1875 - An ice storm on the first day of spring dropped 0.54" of liquid precipitation in temperatures that were below freezing all day (high/low was 31°/22°).

March 23, 1875 - Five of the past six days had highs of 32° or colder.  Average high/low during these six days was 31°/18°.

March 18-19, 1876 - Lows of 9° on both days.

March 10, 1877 - The day after the mildest reading of the month (57°), the temperature at daybreak was 21°.  This was the first of eleven days in a row in which there were no highs milder than 40°; four days in a row would see lows in the teens (coldest reading was 10° on 3/19).  The average high/low during this very cold outbreak was 32°/22°.

March 19, 1877 - Yesterday's and today's frigid highs and lows of 26°/12° and 22°/10° were comparable to the Arctic cold experienced on the same two dates the previous year (30°/9° and 27°/9°). 

March 12, 1883 - This was the tenth day in a row with highs colder than 40°.  High/low during this time was 33°/17°.  Two snowfalls during this streak amounted to 5.5".

March 30, 1883 - A snowfall of 4.5" was the sixth snowfall of four inches or more this winter (this was despite the fact that no measurable snow fell in December).

March 1-5, 1884 - The month began with five days with highs of 30° or colder, with two reporting highs of 21° and one, a high of 18°.  Average high/low during these days was 23°/12°.

March 30, 1884 - It was a very late date for a sub-freezing high temperature (31°) at a time of the month when the average high is around 50°.

March 18, 1885 - Today's low of 8° was the 18th in the single digits or colder this winter, breaking a tie with the winter of 1872-73 for most on record (later passed by the winter of 1918, which had 20 frigid lows).

March 24, 1885 - This was the eighth day in a row with lows in the teens or colder.  The average low during this stretch was just 13°.  (March 1885 is the third coldest on record).

March 21, 1887 - Today's high of 49° was the mildest reading this March - the only March with its mildest reading below 50° (it would happen a week later as well).  By comparison, January and February each had a reading in the low 60s.

March 29, 1887 - The temperature fell slowly throughout the day, from 29° shortly after midnight to 19° nearly 24 hours later.

March 2-25, 1888 - Thirteen of the days had highs of 35° or colder and fourteen had lows in the teens or colder.

March 12, 1888 - The Blizzard of '88 (also known as the Great White Hurricane) roared into an unsuspecting New York during the morning and brought the City to a standstill for the next few days.  16.5" of snow fell today, with an additional 4.5" falling tomorrow into the early morning hours of the 14th.  This was New York's biggest snowstorm until Dec. 1947 (it's now ranked fourth).  In addition to the large amount of snow, the storm's danger was magnified by mountainous snow drifts created by winds that gusted between 45 and 55 mph, and extreme cold, as the temperature dropped from 33° to 8°.  

March 13, 1888 - A bit more snow (three inches) fell today from yesterday's blizzard, but what stood out  was the extreme cold (even by mid-winter standards) as the high/low was just 12°/6° - the second coldest day ever experienced in March (the high/low on March 5, 1872 was 10°/3°).  With gusty winds still prevalent, wind chills were below zero.  This was the fourth March in the 1872-1888 period to have two or three days with lows in the single digits; since then it's happened in just one other year (in 1916).

March 19, 1890 - A late season snowfall of six inches was the largest accumulation of the winter, beating the snowfall of Dec. 14 by half an inch.  March 1891 had four snowfalls of three inches or more; they totaled 17.1", which is the tenth greatest accumulation for the month.

March 2, 1891 - The morning low of 9° was the coldest reading all winter.  This was similar to last year when the only reading in the single digits was also in March (7° on 3/7). 

March 18, 1892 - Snow that began falling late last night continued through this morning and accumulated eight inches (the 7.2" that fell today is the most to fall on 3/18).  This was the biggest snowfall of the winter (passing a six-inch snowfall on 1/16) and came in the midst of an unseasonably cold 12-day stretch (March 11-22) in which the high low was a cold 34°/22°.

March 15-16, 1896 - Less than two weeks after a snowfall of ten inches on March 2, an even bigger snowstorm dumped a foot of snow.  (And in between these two storms, four inches fell on 3/12.)  It began early in the afternoon of the 15th and by midnight 6.5" fell; an additional 5.5" fell the next day through midday.  Then the snow changed to rain as the temperature rose into the mid-30s.  Then on 3/23, 4.5" fell, bringing the month's total snowfall to 30.5".  This would be Central Park's snowiest month until Feb. 2010, and is now ranked third (Jan. 2011 also had more).  High/lows of 28°/15° on 3/24 and 32°/23° on 3/27.

March 11-18, 1900 - Lows were 22° or colder for eight consecutive days.  The average low was 16°.

 

Womens muff

 

 


A Taste of Summer: The Year's First High of 80+

 First
Since 1980, the average date of the first reading of 80° or warmer is April 21 (a month later than the average date of the first reading of 70°+).  This is about a week earlier than 1900-1979, and two weeks earlier than the 1869-1899 period.  It's happened as early as March 13 (in 1990) and as late as June 7 (in 1924).  1918, 1927, and 2010 had their first reading of 80+ occur on the same date as each year's first high in the 90s. 

 

The average high temperature on the day before the first 80+ reading has been 70°, on the day of the first 80+, it's been 83°, and the high on the day following has averaged 74°. 

 

About one-third of the years have had a day of 80° or warmer on the day following the first 80+, but 16 years didn't have their second high of 80°+ for four weeks or more.  The greatest number of days to elapse before the second 80+ reading was 57 in 1928 (April 6-June 1).  The most recent lengthy hiatus was 41 days in 2013 (April 10-May 20).

 

Eight years have had their first 80+ high in March.  The first time it happened was in 1921, the most recent occurrence was 100 years later, in 2021.  Meanwhile, a first 80+ in June has occurred just once (1924).

 

Chart - earliest and latest first 80

 

On the day with the first high of 80° or warmer, the diurnal variation has averaged 27 degrees (this compares to a 14-degree variation for any day of the year).  The  greatest variation was 43 degrees in 1929, when the high/low was 89°/46°.   The smallest variation was 16 degrees in 1908 (81°/65°).

 

Chart - greatest diurnal variation on day of first 80
 

The chilliest low on the day of  the first 80+ reading was 43° in 1936 and, again, in 1990.  The warmest low was 68° in 1898.  The chilliest day-before high was 49°, in 1977.  The chilliest day-after high was 50° in 1921, and 51° in 1939.

 

29 years (about once every five years) had a warmer reading on the day after the first 80+ reading.  The warmest day-after reading was 93° in 1988.   The last time the day-after was warmer was in 2009, when the  high was 92° (the first 80+ reading that year was 88°).  The warmest day-before reading was 79°, which has happened in four years, most recently in 1955.  (And ten other years had a day-before high of 78°.)

 

April 19 is the date that's had the most first 80+ occurrences - in ten years.  And it's happened in seven years on April 25.   The most consecutive years to have the first 80+ occur in May is six, from 1873-1878. 

 

There have been six pairs of years in which the date of the first 80+ was the same:

> April 18, in 2015 and 2016

> April 15, in 2002 and 2003

> April 19, in 1972 and 1973

> April 26, in 1969 and 1970

> May 16, 1931 and 1932 (and in 1933, the date was 5/15)

> April 19, in 1914 and 1915

 

There have been fiver pairs of years in which the dates of the first 80+ were at opposite ends of the early/late spectrum.

> 1997 - May 19/ 1998 - March 27

> 1988 - May 23/ 1989 - March 28

> 1984 - May 23/1985 - March 29

> 1945 - March 20/ 1946 - May 25

> 1920 - May 28/ 1921 - March 21

 

Finally, measurable rain has fallen on the day of the first 80+ reading in 20% of the years (similar to the day of the first reading of 70+).  The biggest rainfall on this date was 0.67" in 1984 (May 23) as afternoon thunderstorms moved in after the temperature peaked at 81°; the second most was 0.60" in 1951 (4/29).

  80 plus

 

 


Months With 20" or More of Snow

20

 

During the winter of 2021, February became the 36th month (since 1869) to have 20 inches or more of snow fall in Central Park.  This was the seventeenth February to gain this distinction, by far the most of any month (January's had eight occurrences; December's had six; and March, five).  Thirty winters have had one of these snowy months, and three have had two (winters of 1978, 1996, and 2011).  19 of the months with 20"+ had more than 25" (including Feb. 2021).  And four had 30" or more.  The snowiest month of them all is February 2010, which reported 36.9".  Below are more observations about these snow-choked months: 

  • The first month with 20" or more snowfall was December 1872, when 27.0" was reported.  Despite February being the month most likely to have 20"+ snow, it didn't have its first overly snowy month until 1894, which was later than the first 20"+ occurrence for December, January or March.  (November and April have never had 20" or more; however, November 1898 came very close, with 19.0".  The most snow in April was in 1875, when 13.5" was measured.)
  • The most consecutive winters to have a month with 20"+ snow is just two, which has happened five times, most recently during the winters of 2010 and 2011.  The most consecutive winters without one of these snowy months is twelve, from 1936 thru 1947.  And there have been three ten-year gaps.

 

Chart - consecutive winters with 20 inches

  • The most days of measurable snow during a month with 20"+ is eleven, which occurred in March 1916 (25.5" fell) and February 1920 (25.3").  The fewest days of measurable snow during a 20"+ month is two, in February 2006, when one storm accounted for all of the month's 26.9" (at the time, New York's biggest snowfall on record).  And in January 2016 there were three days of snow, with 27.5" of the month's 27.9" falling on two of the days (which supplanted February 2006's snowfall as New York's biggest of all time).

 

Chart - most days of snow in month

 

Snow at radio city

 

  • Nine of the thirty-six excessively snowy months had no snowfalls of a foot or more; five had biggest snowfalls that were less than ten inches.   The smallest biggest snow was 7.0" in Dec. 1904, followed by March 1916, whose biggest accumulation was 7.6".
  • In a winter with a month of 20"+ snow, the least total snowfall for the entire winter was the winter of 1979, which had 29.4"; the 20.1" that fell during February of that winter comprised slightly more than two-thirds of the winter's total.  And in the winter of 1925,  29.6" of snow fell, of which January 1925 accounted for all but 2.2".
  • Two of New York's ten snowiest winters had no months with 20" or more: 1874-75 is ranked seventh,  and 1960-61 is the City's ninth snowiest winter.

 

Chart - snowiest winters with no 20-inch months
 

  • All but five of the thirty-six months were colder than average, including the coldest month on record, February 1934 (which had 27.9" of snow), the coldest March on record (1888, 22.3"), and fifth coldest December (1872, 27.0") and March (1916, 25.5").   The most above-average month to have more than twenty inches of snow is December 1948 (+3.9 degrees), followed by February 1983 (+3.0 degrees); January 2016 (+1.9 degrees);  February 2006 (+0.4 degrees); and February 1994 (+0.2 degrees).
  • Finally, "honorable mentions" go to December 2003, which had 19.8", and January 2014, which had 19.7".

 

Feb 1 snowstorm nbc nightly news

 

Here are a number of other posts I've written which discuss snowstorms in New York:

Comparing New York's Three Biggest Snowstorms

A History of Back-to-Back Snowstorms

New York's Snowiest 30-Day Periods

Remembering New York's "Snowmageddon" of Winter 2011

Survey of New York Snowstorms by Winter (1950-2021)

 


Analysis of Back-to-Back Days With the Same High & Low Temperatures

The same

 

In the years I've spent poring over New York's daily weather data, I'd notice pairs of days with the same high and low.  This analysis is the product of my curiosity about how common such pairings are.  On average, two occur each year (2.3 to be exact).  The most has been ten, which happened in 1931 and 2010.  There have been ten years with five or more pairs, including 2020.  Twelve years have had none.  (Of course, if temperatures were reported to one decimal place, these type of days would be even rarer than they already are.)  Here are some more interesting findings:

 

  • There have been three streaks that had three consecutive days with identical highs/lows - in 1988 (Aug. 3-5, all with a high/low of 89°/76°); 1984 (May 5-7, highs/lows of 69°/53°), and 1879 (May 8-10, 69°/49°).  And during the summer of 2013, after a high/low of 83°/67° on July 30-31, there was another day with the same high/low two days later, on Aug. 2.
  • There have been 23 pairs that missed by one degree of having a third consecutive day with the same high/low.  The most recent occurrence was in December 2010, when 12/7 had a high/low of 36°/30° after a high/low of 35°/30° on 12/5 and 12/6.  And each of the streaks of three-days (mentioned above) narrowly missed being four-day streaks:
    • Aug. 3-5, 1988's streak missed being a four-day streak when the high/low on Aug. 6  was 89°/75° instead of 89°/76°.
    • May 5-7, 1984's streak of 69°/53° was followed on May 8 by a high/low of 69°/55°.
    • The day before 1879's streak of May 8-10, with highs/lows of 69°/49°, the high/low was 70°/50°.
  • There have been three back-to-back pairs of days: July 28-31, 2010 (89°/74° on 7/28-29 and 85°/66° on 7/30-31); March 3-6, 1952 (pairs of 36°/32° and 42°/31°); and Aug. 17-20, 1906 (pairs of 85°/71° and 87°/77°).  And there has been one instance of three consecutive pairs of days: Dec. 16-21, 1901 (26°/20° on Dec. 16-17; 28°/20° on Dec. 18-19; and 26°/19° on Dec. 20-21).  (March 1952's and August 1906's streaks narrowly missed having three consecutive pairs.)
  • Of the 12 years with no pair of days, only one occurred after 1956 - 2000.  The other years: 1956, 1954, 1943, 1934, 1930 1924, 1916, 1903, 1889, 1881 and 1869.
  • There have been two instances of back-to-back years having the same pair of dates with the same high/low.  It first occurred on July 27-28, in 1897 and 1898.  (The pair of highs/lows in 1897 was 67°/64°, and 80°/74° in 1898.)  The second time was in 2020 and 2021 on May 29-30 (highs and lows of these pair were 81°/67° and 51°/47°, respectively).  And there have been five instances of pairs of the same dates being two years apart, most recently in 2018, when it and 2016 each had a pair of days on Dec 23-24.
  • July 27-28 has had the same high/low in six years, the most of any pair of dates: 2007, 1988, 1939, 1910, 1898, and 1897.
  • May 18-19, 1932 and May 18-19, 2005 had the same pairs of highs/lows (70°/53°).
  • There have been four pairs of 85°/70° highs/lows, which is the most frequent of any pair  (occurring on July 4-5, 2017; May 27-28, 2015; June 25-26 2014; and June 27-28, 1994).
  • July and August are the months most likely to have seen pairs of days with the same high/low (48 and 51 occurrences,respectively); February and October are the months least likely to report a pair of these days (with just 12 each). 
  • Hottest pair: 100°/79° on July 9-10, 1937; Coldest pair: 23°/14° on Jan. 28-29, 1986.

 Chart - back to back days_same high low

 

 


Dry Months in New York

Drier than normal

 

For the purposes of this analysis a dry month is one that had less than two inches of precipitation.  In the years since 1869, 18% of all months have been this dry, or about two months each year.  The most dry months in one year is six, which happened in 1910, 1946 and 1965.  The most consecutive months with less than two inches measured is four, which occurred in 1881 from July thru October.  Finally, there have been 15 years in which no month had less than two inches - most recently in 2018 (two of these 15 years were consecutive, in 2010 and 2011).

 

Graph - precip of less than 2 inches by month

 

CONSECUTIVE DRY MONTHS WITHIN A YEAR

The most consecutive months with less than two inches of precipitation is four, which happened in 1881 between July-October (1.25", 0.86", 0.97" and 1.60").  There have been nine other years that had three dry months in a row, the most recent being in 1993.  The smallest amount of rain during one of these streaks was 2.98" in 1910 (July-Sept.).

 

Chart - 3 months in a row with less than 2 inches

 

Two of the three years that have had six months with less than two inches of precipitation, 1910 and 1965, are among New York's ten driest years, but the third, 1946, is ranked 27th.

Five Octobers in a row from 1946-1950 had less than two inches of rain.  And there have been three other months that had this little precipitation in four consecutive years: January 1954-57; May 1902-05 and September 1884-87.  And seven of the nine Novembers between 1901-09 had two inches or less.

 

LESS THAN ONE INCH OF RAIN

Nearly one out of four dry months had less than one inch of rain, or about once every two years.  The greatest number of these very dry months in one year is three and it's happened twice, in 1881 and 1955.  The most years in a row to have the same month report less than one inch is two, which has happened three times: July 1954 (0.96") & 1955 (0.51"); Sept. 1884 (0.21") & 1885 (0.41"); and Oct. 2000 (0.68") & 2001 (0.66").

 

DRIEST MONTH OF EACH YEAR

On average, the driest month of a year has had 1.24" of precipitation (and most likely to happen in October).  About 40% of all years have had less than an inch of precipitation during their driest month.  June 1949 is the driest month of all time, with just 0.02" measured; the driest month in recent years is October 2013, which had just 0.36". The most consecutive years with a driest month reporting less than an inch is four, which was between 1999-2002.  

Thirteen years have had more than two inches as their driest month.  And two of them had more than three inches: 3.04" in 1975 and 3.03" in 2011. 

In both 1980 and 1981 the driest month had 0.58" of precipitation, and it was in consecutive months - Dec. 1980 and Jan. 1981.  And later in 1981, August had 0.59".  Two other years' second-driest month also had just 0.01" more than the driest month (1900 and 1975), while 1926's second driest month had 0.02" more.  And in 2000, 2001 and 2002 the driest months had 0.68", 066" and 0.71", respectively.

In the three consecutive years between 1903-1905, May was the driest month, and in the three consecutive years 1945-1947, October was the driest month.  Finally, in the four-year period 1967-1970 three of the years had January as their driest month (1967, 1968 and 1970).

 

Graph - driest month of year since 1869

 

Arid


Notable December Cold Snaps

The weather outside is frightful

Nearly 40% of Decembers since 1869, or 59, have experienced cold snaps/cold waves that lasted five days or longer (about half were seven+ days).  The most recent occurred in 2017.  In addition to the five-days+ qualifier, a cold snap needed to have an average high temperature of 32° or colder to be part of this analysis.  The longest of them lasted 15 days, in 1876; six have had sub-zero readings; six had twelve inches of of snow or more; and six had no snow whatsoever (not even a trace).  Finally, six Decembers had two periods of Arctic cold.

 

COLDEST

The coldest December cold wave occurred in 1917, when the six days between Dec. 17-22 had an average high/low of 17°/2°.  Most recently, the last six days of Dec. 2017 had an average high/low of 23°/15°, which tied for ninth coldest.

 

Chart - coldest december cold snaps

LENGTHIEST

Fifteen Decembers have had cold waves lasting ten or more days.  The lengthiest was 16 days in Dec. 1904 (average high of 32°/22°), followed by a 15-day stretch in 1876 (27°/17°).  The coldest of these lengthy cold waves was one of 10 days in 1872 (24°/10°).

 

Chart - lengthiest december cold waves

 

TWO IN ONE MONTH!

Six Decembers had two significant cold snaps.  The last time it happened was in 1955, with one of five days and the other lasting six days (they were three days apart).  The two in 1917 covered 15 days (eight days apart).

 

Chart - decembers with two cold snaps

 

COLD SNAPS MORE PREVALENT 100+ YEARS AGO

The greatest concentration of Decembers with cold waves was between 1876 and 1904, when 20 of the 29 Decembers had at least one cold snap.  The most consecutive Decembers to have a cold snap is four, which has happened four times: in 1901-1904, 1914-1917, 1932-35 and 1942-45; there have also been four three-year streaks, with the most recent being 1958-1960.  The most consecutive years without a cold snap is eight, and it's happened twice, in 1981-1988 and 2001-2008.  And there was a seven-year hiatus from 2010 to 2016.

 

SNOWIEST & LEAST SNOWY

Six cold snaps received more than 13 inches of snow.  The most was 22.5" in 1883 and 21.5" in 1872.  The most recent was in 2000 when 13.3" fell.  Five of the Decembers had snowstorms that dumped a foot or more, with the most being 18.0" on Dec. 26, 1872.  And although December 1942, with 6.0", isn't found on the "most snowy" list below, it's worth mentioning because it had measurable snow on six of the cold wave's ten days.

 

Chart - snowiest december cold snaps

 

At the other end of the snow spectrum, ten December cold snaps had no measurable snow.  Eight of them were five or six days in duration, but December 1870 and December 1989 lasted 11 and 10 days, respectively.

 Chart - december cold snaps with no snow

BELOW ZERO READINGS

Seven of the Decembers had at least one sub-zero low.  The most recent was in 1980 (on Christmas Day).  These cold waves accounted for all of the twelve sub-zero lows that have been reported in December.  And although December 1872 had no below-zero readings, it had the distinction of having six days in a row with lows in the single digits (ranging from 4° to 8°).  At the other end of the spectrum, the coldest temperatures of five December cold snaps was a relatively mild 18° or 19° (most recently in 1970).

 

Chart - subzero readings in december

 

 

Frigid-cold-blast-to-strike-usa