December 2021 Weather Recap: Mild & Dry

 

 
December 2021 was the third mildest on record (behind 2015 and 2001, and 0.1 degree ahead of 1984), and tied for fourteenth driest.  At 4.7 degrees above average, it was the most above average month of 2021 (passing October, which was 4.1 above average).  Although it ranked third for mean temperature (average of high/low), the month had the second mildest average low, and was tied for seventh mildest average high.

 

Seven days had mean temperatures that were 10+ degrees above average, and eight days had highs of 55° or milder (half of these days were in the 60s).  The mildest reading was 66° on 12/11, which was a record for the date.  Two extended periods of mild temperatures were largely responsible for the month being so mild, as Dec. 11-18 was 11 degrees above average (high/low of 56°/44°), and the last week of December was 8 degrees milder than average (48°/40°).  This was just the seventh December to have no temperatures of 32° or colder in the last seven days of the month. 

 

Six days had lows of 32° or colder (average number for December is 14), with the coldest reading being 25° on 12/20.  Only three other Decembers have had a milder reading as their coldest reading:  2015 (34°); 2012 (28°); and 1974 (26°).  And Dec. 1984's coldest reading was also 25°.  (On average, the coldest reading in December is in the upper teens; before 1970 it was in the low teens). 

 

Like November, December was quite dry, with just 1.39" of precipitation  measured.  Combined, these two months became Central Park's driest Nov.-Dec. on record.  Ironically, this dry combo occurred in one of the ten wettest years on record.  By contrast, the nine driest November-Decembers behind 2021 had about twenty inches less annual precipitation than 2021.

 

 

With the exception of the last week in October, which had 4.71" of rainfall (the wettest last week of October on record), the other 12 weeks between Oct. 1 and Dec. 31 had only 3.06". 

 

December had just 0.2" of snow, which occurred in the pre-dawn hours of 12/24.  However, meager snowfall in December isn't uncommon, as smaller amounts (or none at all) have occurred in five Decembers  since 2001, and nine since 1994 (once every three years).

 

Unusually low humidity was reported on two dates - 20% on 12/14, and 14% on 12/17 (both in the afternoon).  Going back to the early 1940s, 14% is the lowest humidity ever reported in December (the previous low was 16% on Dec. 8, 1981).  Humidity levels below 25% are very rare in December (most instances of low humidity occur in March and April).

 

Finally, the month, and year, ended on a mild note as the temperature at the stroke of midnight was 51° (after a high of 55°).  This was the mildest reading during the ball drop at Times Square since 2004 (and the fifth mildest ball-drop reading on record).

 

 

Other December recaps:

2020

2019

2018

2017

2016

2015

 

 

November 2021 Weather Recap: Dry & Chilly

 

With just 1.12" of rain, November 2021 was the driest November since 1976 (the driest November on record).  The month was also 1.8 degrees chillier than average, making it the most below average month of the year (February and July were  1.7  and 1.5 degrees below average, respectively).  This November was significantly chillier than last November (the mildest on record), as it was 6.8 degrees colder - the biggest temperature drop from the previous November since Nov. 2012.  Only eight other Novembers have had a bigger drop in average temperature compared to the November immediately preceding it.

 

 

Despite its big difference from last November, Nov. 2021 was far from the ranks of the coldest, as it tied for 80th chilliest.  (Fun Fact: All of the Novembers between 1869-1894 were colder than Nov. 2021.)  Still, it had 14 days that were five or more degrees below average.

The month's warmest reading was 69° on 11/18, followed six days later by the coldest reading (30°).  Although this was the latest date for a temperature this mild in six years, it was the first time since 2014 that the warmest November reading failed to be in the 70s.  Of note is that this warmest reading didn't occur during the 6-day period Nov. 8-13, which was six degrees milder than average.

In October, the first low in the 40s wasn't until 10/18, which was the second latest date on record.  In November, however, the fall's first reading of 32° or colder (32° on 11/23) was close to the average date of this occurrence. 

Most of the month's 1.12" of rain fell during two rain events on consecutive days:  0.48" on 11/12, and 0.33" on 11/13.  On the 13th, an uncharacteristic precipitation type for November, hail, fell for a few minutes during a quick-moving thunderstorm.  Another type of frozen precipitation, snow flurries, was reported on the last three days of the month  - but there was no accumulation in Central Park (Newark Airport reported 0.1" on the 28th).

 

Here are recaps of previous Novembers:

2020

2019

2018

2017

2016

2015

 

 

 

 

October 2021 Weather Recap: 6th Mildest October Ends With Soaking Rains

 

 

After unprecedented rainfall in July, August, and September (each month had more than ten inches), it appeared a respite was in store during October, as the first half of the month was the driest since Oct. 2000, with just 0.15" of rain measured.  However, these dry conditions came to an abrupt end in the last week of the month, as 4.71" was measured - the wettest last week of October on record (and eight of the last nine days had measurable rainfall).  Much of the week's rain was produced by a nor'easter on the 25th-26th that dumped 3.69" of rain. 

 

 

The month's other storyline was its mild nighttime temperatures.  There was a record streak of lows in the 60s (13 days), which was also the month's total number of days with lows in the 60s, tying Oct. 1879 for the most on record (the average number of lows of 60+ in October is 4).  Lows during the first 12 days of the streak were in the narrow 60°-62° range; Day 13's low was 63°.  Of the eight longest streaks of lows in the 60s/70s in October, this year's record streak was the coolest.

 

 

Overall, the month was 4.1 degrees above average, and became the sixth mildest October on record (it ranked fourth for average low, and tied for 19th for average high).  17 days were five degrees or more above average; seven days had  below average mean temperatures.  The most above average day was 10/15, which was thirteen degrees warmer than average (high/low of 79°/63°); the most below average day was 10/1 , which was five degrees below average (67°/51°).

 

Temperatures during October ranged from 47° (on 10/19, 10/24, and 10/29) to 79° (on 10/15).  Only three other Octobers have had a smaller temperature range: 1977 (30 degrees); 2004 (31 degrees); and 1894 (31).    This mirrored September, which had a 31-degree variation, and was tied for third smallest variation.

 

In an oddity, there were six days with temperatures stuck in the 60s - the most on record for any month.  They occurred in three pairs, and were concentrated in the nine-day period between Oct. 3-11.  This narrow temperature range was largely due to persistent overcast skies.

 

The season's first low chillier than 50° was reported on 10/18, which was the second latest day for this occurrence (latest is 10/20).  Additionally, the month's chilliest reading of 47° (reported on three days), was the mildest chilliest reading on record for October (on average, the coldest reading in October is in the upper thirties). 

 

Here are previous recaps of October's weather:

2020

2019

2018

2017

2016

September 2021 Weather Recap: A Record-Setting 3rd Month in a Row with 10+ Inches of Rain

 

 

September 2021 will long be remembered for the torrential rain that fell the night of 9/1, submerging streets, highways, subway tunnels and residences.  Nearly 50 deaths in the metro area were attributed to the storm (13 of them were in NYC).  This unprecedented deluge was produced by the remnants of hurricane Ida pushing up against a mass of cool air.  Between 5 PM and 1 AM, a little more than seven inches of rain poured down (with three inches falling between 9-10 PM). 

 

Although heavy rain had been predicted, its intensity in such a brief period of time took residents by surprise.  (And although hurricane Henri, two weeks earlier, produced an inch more of rain than Ida, it fell over the course of 48 hours). 

 

Never before had a month started with so much rain, easily breaking the previous record amount on the first day of a month, 4.98" on Oct. 1, 1913.  The 7.13" measured on 9/1 was the fifth greatest amount to fall on a calendar date.  (Earlier this year, February began with a record amount of snow for the first day of any month, 14.8".)

 

 

The rest of the month had slightly below average rainfall, but just enough to bring September's total to 10.03".  This was the most rain to fall in September since 2004, and it became the sixth rainiest September on record.  It followed the fourth wettest August (10.32"), and third wettest July (11.09").  Never before had Central Park had three months in a row in which each month had more than ten inches of rain. 

 

More than 90% of the month’s of rain was produced by two storms:  7.23” on 9/1-2 and 2.03” on 9/23-24.  0.77” fell on the other 26 days.

 

Looking at temperatures, September was 1.1 degrees milder than average, and was the 26th mildest September (tied with four other years).  However, it ranked 13th for mildest average low, and 55th for warmest high.  12 days in a row (Sept. 12-23) had above average temperatures, a streak of days that was four degrees above average.  The rest of the month was one degree cooler than average.

 

The warmest reading was 85° (on 9/15), the same warmest reading as last September (but it had two days with that high).  Also, both Septembers had seven days with highs in the 80s (the average is eleven).

 

Half of the days had highs between 75°-79°, which was double the average number - and the most to be in this narrow temperature range on record (second most is 13 days in Sept. 1999, 1927 and 1908).  Just five days had lows cooler than 60°, eight fewer than average.  Only Sept. 1971, 1930, 1908, and 1881 had fewer days (all had four). 

 

Finally, the month was also characterized by a narrow range in its temperature extremes.  Typically, September's chilliest reading is around 50°, the hottest around 90°, but this September it ranged from 54° (on 9/29) to 85° (on 9/15).  Only two other Septembers have had a range that was smaller.  (The greatest range in temperatures in September was 55 degrees in 1929, ranging from 44° to 99°.) 

 

 

Here are previous September recaps:

2020

2019

2018

2017

2016

2015

2014

 

 

 

August 2021 Weather Recap: Henri Rescues August From "Dullsville"

 

 

 

August was the fourth wettest August on record, but until 8/21 the month had been a dry one, with rainfall 50% below average.  Then, Hurricane Henri produced 8.19" of rain over three days (Aug. 21-23), accounting for nearly 80% of August's 10.32" of rain.  (The other 28 days of the month had just 2.13".)  This was the second month in a row with more than ten inches of rain (July had 11.09", making it the third wettest July),  just the second time this has happened (however, the first time, in March and April 1983, is disputed since the rain gauge in Central Park wasn't functioning properly for much of the year).  Although August's rainfall was less than an inch below that of July, its number of days of measurable precipitation was half as many (nine vs. eighteen).

 

 

One out of four Augusts have been warmer than July, and August 2021 was one of them (77.5° vs. 76.0°).  The month was 1.4 degrees above average, making it the City's 17th hottest August (out of 153).  However, there was a disparity in rankings of the average high and low, as only five other Augusts have had a warmer average low than this August (2.2 degrees warmer than average), but the average high (just 0.6 above average) was ranked much lower, at #39.  This difference in rankings wasn't unique to this August, as the trend during the 2000s has been for overnight temperatures to be more above average than daytime readings (one of the effects of global warming).

 

After the first five days of the month were five degrees below average, the rest of the month was three above average (with only five of the 26 days having cooler than average mean temperatures).  August had five readings in the 90s, one more than July, and it had five more days than July with lows of 75° or warmer.  August's days in the 90s were comprised of back-to-back days on Aug. 12-13, and a three-day heat wave two days after Henri's departure (Aug. 25-27).  The month's hottest reading was 94° on 8/13.

 

Finally, this was the eighth year in a row in which August had no readings in the 50s.  The coolest temperature was 63° on 8/2.  (Meanwhile, July's streak of 12 years with no lows cooler than 60° was broken this year). 

Here are monthly recaps for past Augusts:

2020

2019

2018

2017

2016

2015

 

 

 

 

 

 

   

July 2021 - Third Rainiest July Keeps Mid-Summer Heat in Check

 

With 11.09" of rain measured in Central Park, July 2021 became the third rainiest July on record (behind 1889 and 1975), and 15th wettest month overall.  This was New York's first month with ten inches or more of precipitation since June 2013 (10.10"), and the most to fall in any month since August 2011, when 18.95" flooded the City (the greatest monthly amount on record). 

 

A little more than half of July's rain fell on three days between July 8-12: 2.27" on 7/8; 2.06" on 7/9, and 1.42" on 7/12.  The amounts of 7/8 and 7/9 set records for the dates.  8.49" of rain fell in the first 12 days of the month (and 9.14" if 6/30 is included), then 2.60" fell thereafter (which was slightly below average for that period). 

 

There were 18 days of measurable rain, which was the second greatest number of days with rain in July.  July 1871 had twenty days, but just half the amount of rain as July 2021.   (Of the 27 months with ten inches or more or precipitation, the average number of days of measurable precipitation is 13.) 

 

Besides being rainy, this was the coolest July since 2009 (and 0.1 degree cooler than July 2014).  When all Julys are considered, July 2021 is in the middle of the pack, temperature-wise, with 54% being warmer.  The combination of a warmer than average June (+2.3 degrees), and July being 1.5 degrees cooler than average, placed these two months closer together (1.7 degrees) than any June/July combo since the summer of 2001 (when July was just 0.3 degree warmer).  Looking at average high and low, July's average high of 83.0 was just 0.5 degree warmer than June's, while the low of 69.0 was 3.0 degrees milder.  Because many days had dew points in the 68°-73° range, the air often felt oppressive rather than cool.

 

 

For the first time since 2009, a reading in the 50s occurred in July - 59° on 7/3.  And on 7/3, the high was only 66°, which was the first high cooler than 70°in July since 2013, and the coolest reading in July since 2005 . The month's coolest and hottest readings were three days apart as a high of 92° occurred on 7/6 (and the 59° reading came three days after June's hottest temperature, 98°, on 6/30).

 

July had four days in the 90s, half as many as June, and the fewest such days in July since 2014, which had three.  (Seven of the Julys between 2000-2009 also had four or fewer days in the 90s.)  Although the number of days of 90+ was half the average for July, the number of lows in the 70s, 16, was an average am0unt (but ten fewer than last year's record amount).

 

July had 8.47" more rain than June's 2.62", but there have been ten other instances where the disparity between two months was even greater (looking only at wet months preceded by dry ones).  The greatest difference occurred in  Sept-Oct 2005, when October had 16.73", which was 16.25" more than September's bone-dry 0.48".

 

Finally, after suffering through sweltering heat, and a nighttime thunderstorm on the last day of June, the last day of July couldn't have been more different, as skies were clear and temperatures on the cool side (high/low of 77°/60°).  While 6/30's high of 98° (14 degrees above average) was the hottest reading on that date since 1964, 7/31's low of 60° (ten degrees below average) was the chilliest since 1956.

 

 

Here are other July recaps:

July 2020

July 2019

July 2018

July 2017

July 2016

July 2015

July 2014

 

 

 

 

 

June Weather Recap: Two 4-Day Heat Waves Make June 2021 One of NYC's 10 Hottest

 

With a scorching high of 98° on the last day of the month (along with a heat index of 106°), June 2021 became New York's ninth hottest June.  This was Central Park's hottest temperature since 2013, and the hottest reading in June since another 98° high in June 1994.  6/30 was also the last day of the month's second four-day heat wave, which was just the second time there were two heat waves of this length (or longer) in June (the other was in June 1943, the hottest June on record). 

 

The month's eight days with 90+ highs were the most in June since June 1991 (which had nine).  Only four Junes have had more hot days: 1943 (11), 1966 (10), 1925 (9) and 1991 (which was slightly cooler than June 2021, ranking as 14th warmest).

 

The month had nine days with lows in the 70s, tying it for ninth most in June.  The month's five days with lows of 75° or warmer was the most since there were six in June 1943.  (June 1909 had the same number as this June.)  Finally, in the years since 1940, the low of 76° on 6/6 was the fifth earliest date for a low this warm.

 

Ironically, despite the month's warmth, this June had the latest occurrence of a reading in the mid-50s since 1995, occurring on 6/23 (54°).  This was the coolest reading of the month (twelve degrees below average).

 

The month's two four-day heat waves were three weeks apart - June 6-9, and June 27-30.  The first heat wave averaged a high/low of 91°/74° (13 degrees above average), the second was 94°/75° (nine above average).  Both heat waves had a day with significant rainfall at night, 0.47" on 6/8, and 0.65" on 6/30.  Without these heat waves, the other days of the month were one degree cooler than average.

 

Besides the high of 98°, the last day of June was also the rainiest day of the month (0.65").  If it hadn't been for this rainfall, this would have been the second June in a row with less than two inches of rain, something that hadn't happened since 1978 and 1979.  These nighttime thundershowers cooled the temperature to 73°, erasing the day's morning low of 80°.  (If that sultry low had remained the day's low, this would have been the seventh, rather than ninth, hottest June.) 

 

With eight days of 90+ readings by 6/30, 2021 joined 20 other years (since 1869) to have this many by that date (1991 had the most - 15).  The last time there was this many by this date was in 1994.  Prior to that, between 1923-1994, this many days in the 90s by the end of June occurred much more regularly, once every four years.

 

Finally, in an interesting contrast, while the last four days of June had highs in the 90s (eleven degrees above average), the last four days of May all had lows in the 40s (ten degrees below average).

 

Here are previous June recaps:

2020

2019

2018

2017

2016

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

 

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. 

 

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

 

March 2021 Weather Recap: Mild & Rainy Last Two Weeks

 

 

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.

 

 

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.

 

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

 

 

 

 

February 2021 Recap: New York Trudges Through One of Snowiest Februarys On Record

 

 

February 2021 was 1.1 degrees colder than average, and the eighth snowiest February on record, with 26.0” measured.  More than half of the snow fell on Feb. 1, when 14.8” piled up (in total, the storm produced 17.4”).  This was the largest accumulation ever reported on the first day of February.  Another highlight of the month was the severe Arctic outbreak in the middle of the month that plunged Texas, the southern Plains, Midwest and Ohio Valley into the deep-freeze, but barely brushed New York.  Although the month was colder than average, the coldest reading was just 17° (the month's only reading in the teens).  The month's colder than average status was driven by the average high, which was 2.7 degrees colder than average; meanwhile, the average low was slightly above average (+0.5 degree).  Finally, with 5.13" of precipitation, the month was among the ten wettest Februarys since 1930 (and 21^st wettest going back to 1869).

 

This was New York's coldest February since 2015 and the first colder-than-average month since May 2020. It was also the first year since 2015 in which neither January or February had any readings of 60° or milder.  The 15-day period between Feb. 7 and 21 was five degrees colder than average (high/low of 35°/25°), with all but one of the days colder than average (10.2" of snow fell during this period).  Temperatures rebounded during the last six days of the month, and were six degrees milder than average (high/low of 48°/38°); temperatures were above freezing for the entire period.

 

Like January, there was just a 37-degree range between February's coldest and mildest readings (17° and 54° in February, 14° and 51° in January).  Since 1950, the typical range has been 49 degrees (11° and 60°); during these year just six other Februarys have had a smaller range, most recently in 2010 (29 degrees).  Meanwhile, the month's average diurnal variation (the difference between the high and low temperature) was just 9.5 degrees (February's average is 13.5 degrees), making it just the fourth February with a diurnal variation less than 10 degrees.  (The others were in 2010, 1969 and 1869.)  This was only the second Jan./Feb. in which both months had diurnal variations less than ten degrees.  (The other time it happened was in 1869.)  Jan./Feb. 2021’s diurnal variation of 9.7 degrees beat out 1869's by 0.1 degree for smallest variation.

 

 

This winter’s December-February combo was the ninth snowiest on record.  It joined four other pairs from this century (the other five happened before the winter of 1962).

 

 

February 2021 joined sixteen other Februarys that had 20 inches or more of snow.  It was milder than all but two of them (February 1983 and 2006).

 

 

Looking at December thru March, February 2021 ranks as the fifteenth snowiest month, just 0.1" behind Feb. 2003, Jan. 1996 and Feb. 1894.  This February's hefty snow accumulation was quite a contrast to last February, which saw just a trace.

 

Here are other February recaps:

2020

2019

2018

2017

2015