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

 
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).

 

 

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°).

 

 

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).

 

 

 

Today in New York Weather History: December 17

 

 

Dec. 17 is the average date of the first high temperature of 32° or colder (based on the period 1970-2020).  It's happened as early as Nov. 22 (in 2008) and Nov. 23 (1989), and as late as Jan. 20 (1986).  In more than half of the years the first high of 32° or colder was 31° or 32°, but it's been as cold as 20° (which happened in the winter of 2007-08, when it occurred late, on Jan 3).   

 

1904

A snowfall of six inches (three inches this evening, three inches tomorrow morning) came four days after a snowfall of seven inches.

1919

Four days after the temperature reached 61°,  tonight, shortly before midnight, the mercury dropped to one degree above zero.  This was the first of fifteen days this winter with lows in the single digits or colder.

1932

Snow that began late in the morning continued through early morning on 12/18. amounting to 7.2".  It was also a very cold day, with a high/low of only 21°/10°.  (The snow was gone by Christmas Day, which had a high of 59°.)  The next measurable snowfall wouldn't be for another seven weeks (2/4).

1951

Today's frigid high/low of 20°/8° (22 degrees below average) would be the coldest day of the winter.  Skies were clear.

1971

This was the twelfth day in a row with above average temperatures.  During these dozen days temperatures were ten degrees above average.  Even after passage of a cold front early this morning, and temperatures falling throughout the day, the mean temperature was five degrees above the norm.  This stretch of mild weather followed a two-week period of colder than average weather. 

1973

The epic ice storm that began yesterday afternoon continued through this morning.  Conditions were worse than yesterday as sleet and freezing rain fell at an even heavier rate.  In total, 1.46" of precipitation fell - all in the form of sleet or freezing rain.  The temperature stayed below freezing all day, and by midnight had fallen to 17°. 

 

1996

Light showers through early afternoon amounted to 0.12".  This was the 146th day this year with measurable precipitation, establishing 1996 as the year with the most days of precipitation in the 20th century, passing 1972, the previous crown holder.  And there would be six additional days of precipitation before the year ended.  (The average number days of precipitation per year is 121.)

1998

Today was the 25th day in a row with above-average temperatures.  During this stretch of mild days temperatures were ten degrees above normal.  This would be the mildest December since 1984.

 

2000

Today's high of 62° was a record for the date, just one of five days with above-average temperatures during a December that was quite cold (5.5 degrees below average) - the coldest since 1989. 

2001

This was the 18th day in a row in which no low temperature was duplicated.  During these days (beginning on Nov. 30) they ranged between 32° and 58° - all above average.

2012

Only three degrees separated the day's high (43°) and low (40°) on a raw, "gloomy Gus" kind of day. 

2013

Light snow, occasionally mixed with sleet, fell throughout the daytime hours and amounted to 1.5".  This was the fourth snowfall of the past ten days, totaling 8.6".  Three of these snow "events" delivered one-inch+ - the most such snowfalls in December since 2005.  Besides being snowy, the ten days since 12/8 were also quite cold, with the average high/low of 35°/26°, nearly eight degrees below the norm.  

 

2015

It was a mild and rainy day.  The 1.25" of rain that was measured in Central Park fell mostly between 11 AM and 4 PM.  This was the eighth day in a row that had a mean temperature more than 10° degrees above average.  The average high/low during these days was 63°/52° - nineteen degrees above average.

2016

Six days after the first measurable snow of the winter (0.4"), today saw the first snowfall of one inch or more as 2.8" accumulated between 4-8 AM.  Then it changed to sleet, then to freezing rain, all of which was over by noon.  (By contrast, last winter's first one-inch snowfall wasn't until 1/23 - the blizzard that buried the City under its biggest snowfall on record.)

 

2018

Light wraparound showers in the wee hours of the morning (amounting to just 0.03"), remnants from yesterday's rainstorm, made this the 152nd day this year with measurable precipitation, tying 1996 for the all-time record.  What distinguishes 2018 from 1996 is that its total precipitation for the year was more than five inches above 1996's (with two weeks remaining in 2018).

2021

Just three days after Central Park registered its lowest humidity level in December this century (20% later in the afternoon), today had an even lower humidity level - 14% (also during late afternoon).  As low as this was, it was twice as high as the 7%  humidity reported on 4/6 of this year.

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Stuck in the 70s

 

Despite what the headline suggests, this post isn't about people obsessed with 1970s pop culture.  Rather, it's a discussion about days that have had both their high and low temperatures in the 70s.  These type of days have occurred infrequently - about once or twice each year.  33 years (since 1869) have never registered such a day, 53 have had one instance; the most days in one year was ten, which happened in 1905.  In 2017 and 2018 there were five occurrences, joining just ten other years that have had five or more (see chart below).  Temperatures stuck in the 70s usually occur when tropical air is in place, the day is hazy/overcast, and rain is in the air. 

FURTHER DETAILS

• The warmest low in the 70s to be accompanied by a high temperature below 80° is 74°, which has happened twice - first in August 1901, and then seventy-two years later in August 1973.  Both dates had a high of 79°.  (For reference, the average high when lows are between 70°-74° is around 86°).
• The most consecutive days with temperatures in the 70s all day is five, in 1905 (Aug. 30-Sept. 3).
• The most consecutive years without any "all-70" days is four, from 1962 to 1965 (and six out of seven years from 1962 to 1968).  By contrast, there were 21 of these days in the three-year period 1905, 1906 and 1907; they had ten, five and six of these days, respectively.
• The first decade of the 20th century had more "stuck in the 70s" days than the next three decades combined (38 vs. 37).  The 1890s had the second greatest number - 34. The decade that just ended, i.e., the 2010s, had 26 occurrences.
• The latest occurrences for a high/low in the 70s were in 2017, on Oct. 8 and 9 (at the time, the 9th was the latest date for a low in the 70s - until the following year).  The earliest occurrences were on June 4 and 5 in 1960.
• The dates most likely to have experienced a day entirely in the 70s are: 7/23, 7/29, 8/9, and 8/12 - all of which have had seven such occurrences.
• One out of four of these days either had no measurable rain (half were before 1935), while another one out of four received more than a half-inch of rain.  The greatest rainfall was in 1990, when 4.64" fell on Aug. 10 (the high/low was 76°/70°).  Three other days with substantial rainfall were associated with Hurricanes Connie and Irene, in Aug. 1955 (2.70") and Aug. 2011 (2.88"), respectively, and tropical storm Fay in July 2020 (2.54").

 

 

September 2016 Weather Review - Summer Hangs On

September 2016 was characterized by seasonable temperatures at both the beginning and end of the month and unseasonably warm conditions during the days in between (Sept. 6-23); temperatures during this summery two-and-a-half week period were nearly seven degrees above average.  As a whole the month was 3.8 degrees warmer than average, tying Sept. 1983 and 1884 as the tenth warmest on record (this followed the third hottest August).  Three days had highs in the 90s and seven had mean temperatures that were ten degrees or more above average (one of which was the first day of autumn).  There were just five days with below average temperatures.  The most below average was 9/30, with a high of 59/56 (it was the high that was below average, by 11 degrees) - this was the first day in September with a high in the 50s in fifteen years. 

 

 

OTHER SEPTEMBER HIGHLIGHTS

• The high on Labor Day was 84°, which was the same as Fourth of July and very close to Memorial Day's high (82°).  This was just the third time since 1970 that that three summer holidays had very similar highs.  But whereas Memorial Day's high was seven degrees above average and Labor Day's five above, 4th of July's was at the seasonal average.

• On Sept 11 the heat index was 101°.

• The three 90-degree days in September brought the year's total to 22, five above average and the most since 2010.  The 91-degree reading on 9/14 was the latest high in the 90s since 1995 (when it occurred on 9/15).

• Although September's rainfall was below average, more fell than in August (2.79" vs. 1.97").  There were no storms that produced an inch or more of rain but three had a half-inch or more (on 9/14, 0.56" poured down in an hour during a late afternoon thunderstorm).  The rainiest day was 9/19 when 0.68" fell.  Since March, all but one month (July, with 7.02") has had below average rainfall, resulting in a deficit of nearly 10 inches in these seven months (20.91" vs. 30.78") .

 

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Longest Streaks of Above Average Temperatures

 

What helped December 2015 become the warmest on record was the lack of any cold outbreaks whatsoever.  The coldest temperature was 34°, the first time the month of December reported no temperature of 32° or colder.  This lack of cold weather resulted in above average mean temperatures every day of the month - a first for any month.  This streak of above-average temperatures continued through Jan. 3.  At 34 days it's the longest on record, breaking the former record by two days.  Additionally, this streak was 12.5 degrees above average, the largest departure of any streak of 20 days or more, all of which are listed below.  (Please note that, unlike other weather statistics, the tracking of each day's "Departure from Average" only goes back to 1953.) 

 

# of Days			Date Range	Degrees Above Average
34 32       30  27  25  25 24 22 22 22 22 21 21 21 21 21 20 20 20			Dec 1, 2015 - Jan 3, 2016 Dec 10, 2006 - Jan 10, 2007 Jan 15 - Feb 13, 1998 Aug 17 - Sept 12, 1983 Nov 23 - Dec 17, 1998 Mar 13 - Apr 6, 1953 July 13 - Aug 5, 1995 Sept 20 - Oct 11, 2007 Feb 17 - Mar 10, 1998 Aug 24 - Sept 14, 1961 Feb 14 - Mar 7, 1961 June 28 - July 18, 2012 Dec 3 - 23, 1999 Jan 15 - Feb 4, 1990 July 29 - Aug 18, 1988 Sept 21 - Oct 11, 1959 Jan 23 - Feb 11, 2012 Nov 20 - Dec 9, 2011 Mar 24 - Apr 12, 1981	12.5°        11.7°          6.9°          6.4°          9.9°          6.6°          5.8°          8.7°          7.7°          8.7°        10.4°          5.7°          6.9°        11.5°          7.2°          9.5°          8.7°          8.4°          9.4°

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November 2015 - New York's Mildest November on Record

Another warm weather trophy was placed in 2015's trophy case as November pushed aside November 2001 to become the mildest on record - by 0.1 degree.  It follows the warmest September, third warmest August and second warmest May.  Although the month's average high was 0.5 degrees cooler than November 2001's, it pulled ahead with an average low that was 0.6 degrees milder.  (The last day of the month was a nail-biter with a cooler than average high/low of 47°/33°.)  This November was 11.4 degrees warmer than average during the first week of the month while November 2001 was the reverse, experiencing its most unseasonably warm period during the final week of the month, averaging 13.6 degrees warmer than normal. 

 

Besides the mild temperatures both months were on the dry side, with November 2015 picking up 2.01" of rain and 2001, 1.36".  (Average amount is 4.02".)   All but 0.07" of 2015's rain came from two storms while much of 2001's came from one rain event.  

 

The following chart provides a side-by-side comparison of November 2015 and 2001:  

2015    2001 Mean Temperature           52.8      52.7 Average High                    59.3      59.8 Average Low                     46.2      45.6 Highest Temp                     74°       75° Coldest Temp                     32°       34°  Highs of 60°+                     14         15 Days w/Mean Temp 10°+    7          8     Above Average Days w/Below Average        5          7     Mean Temp    Total Precipitation            2.01"     1.36" Days of Precipitation            6         6

 

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New Record Set for Most Days with Highs of 80 Degrees+

 

1944 ceded its #1 position to 2015 twice in regards to warm-temperature records.  First to fall was a streak of 80-degree+ days, which 2015 topped by three days (62 vs. 59); then a few weeks later 2015 once again passed 1944, this time to become the year with the most total days above 80°; by the end of September the number had risen to 114 vs. 1944's former top total of 108.

 

 

In a typical year nearly one-fourth of the days have highs in the 80s, but in 2015 one-third were 80°+.  However, the number of those days that were in the 90s was just slightly above average (20 vs. 17), ranking it 32nd among all years since 1900.  Among the ten years with the most 80°+ days (see chart below), 2015 had the fewest that were 90° or hotter.  As a result, the average temperature of 2015's days that were 80° or warmer was lower than all the other years (by one to three degrees). 

 

2015 set one more record pertaining to 80°+ days as every day in  August had highs of 80°+.  Previous to this year the most 80° days in that month was 28.  This tied July 1944 as the only month to have every day in the 80s or warmer.  (And May 2015 set the record for most 80-degree days in May, with 18.)

 

MOST 80-DEGREE+ DAYS
(Since 1900)
	# of Days		Average
	80+	90+	High
2015	114	20	85.2°
1944	108	37	87.5
1991	105	39	87.8
1959	104	27	86.6
2005	100	23	86.3
1949	100	29	86.5
2010	99	37	88.1
1983	98	36	87.8
1966	98	35	87.9
1941	98	29	86.4

 

Summer of 2015 Highlighted by Record Streak of Days Above 80 Degrees

 

The Arctic air that was entrenched over the Northeast during the harsh winter of 2015 became a distant memory later that summer when New York experienced 62 days in a row with high temperatures of 80° or warmer (July 10-Sept. 9).  This was a record streak, besting the previous record from 1944 by three days.  (On the day the streak ended the high was 79°.)  Of course, summertime temperatures in the 80s or warmer aren't unusual; what was unusual is that for nine weeks there were no incursions of Canadian air or back-door cold fronts from New England.  (These are responsible, on average, for twelve days with highs in the 70s or cooler in July and August.)  The average high during these weeks was 87.5°, five degrees above average.  Below are some other tidbits of interest:

 

• This year's streak joined ten others that were five weeks or longer.  Among them, four have occurred since 2005.

• 2015's s streak included 19 days in the 90s, but 1944's and 1966's (second and fifth longest, respectively) had even more, 30 and 23.  And among the ten longest streaks, the streak in 1966 was the hottest, with an average high temperature of 91°.

• 2015's streak was instrumental in making the August 2015 the third hottest on record and July/August the fifth hottest.

• Finally, this year's streak of warm days matched a streak of cold weather during the winter when another record was set - 61 days in a row with high temperatures that never went above 45°. 

 

LONGEST STREAKS OF 80-DEGREE+ HIGHS
# of			Average	Days	Days
Days	Year	Dates	High	90s	80-81
62	2015	July 10 - Sept 9	87.5	19	4
59	1944	June 26 - Aug 23	89.7	30	5
41	2011	July 4 - Aug 13	88.8	17	1
41	1943	July 8 - Aug 17	87.4	14	1
40	1966	June 20 - July 29	91.0	23	2
37	1917	July 16 - Aug 21	86.1	5	3
36	1999	July 15 - Aug 19	89.5	17	2
35	2008	July 7 - Aug 10	86.4	7	7
35	2005	Aug 20 - Sept 23	84.2	3	6
35	1998	July 9 - Aug 12	85.5	3	3
35	1953	June 18 - July 22	88.6	15	2

 

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Near-Record Warmth of May 2015 Mirrored February's Near-Record Cold

After the harsh February we experienced (the third coldest on record) you might think New Yorkers would be well aware that May 2015 was unusually warm.  Yet most of my friends seemed surprised when I told them that it was the second warmest on record (after May 1991).  They seemed to think the temperatures we experienced were typical.  Yes, it was normal - for June.  May's average high of 78.4 (nearly eight degrees above average) was only one degree lower than what the average high in June is. 

 

Perhaps they took little notice because there was no excessive heat, i.e., no readings in the 90s.  In fact, among the eleven Mays that have had 11 or more days in the 80s, May 2015 was the only one with no 90-degree readings.  However, there were 18 days with highs of 80° or warmer, a new record, passing May 1991's seventeen.  (A typical May has six such days.)  Conversely, it had the fewest days with highs cooler than 70°, just three (the average is twelve).

 

May 2015 ended up being 0.2 degrees cooler than May 1991.  This was due to the fact that 1991 had five days in the 90s.  (The average high of the days that were in the 80s or warmer this May was 83.8° while the days in the 80s in May 1991 averaged 86.5°.)  However, this did become the May with the mildest average low, 0.1 degree warmer than May 1991.

 

 

Besides the warm temperatures May was also very dry - until the last day of the month.  Through May 30 just 0.40" of rain had fallen, and it appeared this was going to be the first May since 1964 to have less than an inch of rain.  Then strong thunderstorms moved in around 5PM, and 1.46" of flooded the City in just a few hours.   

 

COMPARING THE TWO WARMEST MAYS
(1991 & 2015)
	2015	1991
Average High	78.4	78.9
Average Low	58.6	58.5
Mean Temperature	68.5	68.7
Days of 80+	18	17
Days of 90+	0	5
Hottest Temperature	88	93
Lows of 70+	3	4
Lows in the 40s	3	3
Highs Cooler Than 70	3	7

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Warm Weather in May

 

The month of May typically sees six days with highs in the 80s or above, three of 85+ and one reading in the 90s (although it happens in only two out of five years).  Going back one hundred years (to 1915) there have been seven Mays with no 80-degree days (most recently in 2003 and 2005), while May 2015 had the most - eighteen (but no 90-degree readings).  Meanwhile, May 1991, the warmest on record, had the most days in the 90s (five).  However, the hottest readings didn't occur that year: 1962 has that distinction, with a high of 99° on May 19, followed by 97-degree days on May 30, 1969 and May 31, 1987.  And going back to the 1870s, three dates - 5/1, 5/13 and 5/14 - have never had a high in the 90s.

 

MOST 80-DEGREE DAYS IN MAY
(Since 1915)
	80+	85+	90+	Hottest
2015	18	10	0	88
1991	17	10	5	93
1944	14	7	1	92
1977	13	4	2	92
2010	12	5	1	92
1965	12	6	4	94
1959	12	8	3	94
2007	11	5	2	91
1986	11	8	3	94
1964	11	5	2	94
1962	11	6	3	99
FEWEST 80-DEGREE DAYS IN MAY
	80+	85+	90+	Hottest
2005	0	0	0	79
2003	0	0	0	79
1983	0	0	0	79
1928	0	0	0	79
1927	0	0	0	79
1924	0	0	0	75
1915	0	0	0	79
1997	1	0	0	83
1968	1	0	0	80
1917	1	0	0	84

 

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