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 was 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 to occur was in 1990 when 4.64" fell on Aug. 10 (the high/low was 76°/70°).  Two other days with substantial rainfall were associated with Hurricanes Connie and Irene, in Aug. 1955 and Aug. 2011, respectively.

 

 

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 chart below 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 degrees 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 90-degree reading (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 (my birthday) - 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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Unlike Rest of World, 2014 Was Far From Warmest Year in New York

Scientists at the National Oceanic & Atmospheric Administration (NOAA) reported on Friday (1/16) that the Earth experienced its warmest year on record in 2014.  However, the story was different in New York City as 2014 was the coolest in five years.  (And in the past 50 years two-thirds of the years were warmer than 2014.)  Seven months last year experienced cooler than average temperatures, with January, February, March and November being especially below average.   And during the summer only eight days saw 90-degree readings (average number is eighteen), with the hottest being just 92°.

 

MONTHLY DEPARTURE FROM AVERAGE: 2014 (DEGREES)
January	-4.0
February	-3.7
March	-4.8
April	-0.7
May	+1.6
June	+1.0
July	-0.4
August	-0.7
September	+1.7
October	+2.7
November	-2.4
December	+3.2
ANNUAL	-0.8

New York's warmest year was 2012 (2.8 degrees warmer than 2014), just 0.1 degree warmer than 1990, 1991 and 1998.  Four of the Earth's ten warmest years are also among New York's top 10.  Despite the overall warming trend, two of our warmest years occurred more than 60 years ago (1949 and 1953).

 

10 WARMEST YEARS IN NEW YORK CITY
	Mean
	Temp
2012	57.3
1998	57.2
1991	57.2
1990	57.2
1953	57.0
1949	56.9
2006	56.8
2010	56.7
1999	56.5
2011	56.4
2002	56.4
30-Year Average	55.3
2014	54.5

Although NYC wasn't as warm as the rest of the world in 2014, it's important to keep in mind that rising ocean levels resulting from the steady warm up will still effect us.  

 

Autumn Warm Spells - When Summer Keeps Hangin' On

Although the general public often refers to warm spells in the fall as "Indian Summer," most occur before the first frost arrives (which, compared to the suburbs, comes weeks later to Manhattan/Central Park).  This analysis goes back to 1950 and looks at warm spells that have occurred mostly in October and November (with some beginning in late September).  For my purposes I focused on those that were at least four days in length.

 

 

LENGTHIEST

Two-thirds of the years since 1950 have had warm spells of four or more days (including the past seven years, 2010 thru 2016).  Sixteen years had two or more, with 1953 experiencing four.  There have been ten warm spells that lasted ten days or more, the most recent being in the autumn of 2006.  The lengthiest was twenty-one days, which has occurred twice, in 1959 and 1984.

 

MOST ABOVE AVERAGE

There have been thirty-nine warm spells in autumn that averaged ten degrees above average or more (based on daily mean temperature).  The five-day heat wave of Sept. 22-26, 1970 was the most above average, +18 degrees, with four of the five days experiencing highs in the 90s. 

 

LENGTHIEST AUTUMN WARM SPELLS
(SINCE 1950)
		# of	Average		Degrees
Year	Dates	Days	High	Low	Above
1959	Sept 21-Oct 11	21	81	65	+11
1984	Oct 11-31	21	70	57	+ 8
1973	Sept 27-Oct 15	19	74	57	+ 6
1995	Oct 2-14	13	76	58	+ 7
1986	Sept 23-Oct 4	12	79	64	+ 8
1979	Nov 18-28	11	65	52	+14
1994	Oct 30-Nov 9	11	69	52	+ 9
1990	Oct 6-15	10	80	65	+13
2006	Nov 8-17	10	63	53	+10
1970	Oct 6-15	10	74	60	+ 9
WARM SPELLS WITH GREATEST DEPARTURE
FROM AVERAGE
		# of	Average		Degrees
Year	Dates	Days	High	Low	Above
1970	Sept 22-26	5	90	72	+18
1950	Oct 29-Nov 2	5	79	58	+17
1979	Oct 20-23	4	81	65	+16
1991	Nov 19-23	5	67	54	+16
1954	Oct 10-15	6	82	64	+15
1961	Nov 3-6	4	73	59	+15
1963	Oct 24-27	4	79	57	+15
1979	Nov 18-28	11	65	52	+14
1971	Oct 26-Nov 3	9	72	60	+14
1975	Nov 2-10	9	72	57	+14
2007	Oct 3-9	7	82	66	+14

 

 

 

 

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