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Spring Awakening - The Year's First High Temperature in the 70s

70+

 

So far this century, the average date for the first reading of 70° or warmer in Central Park has been March 19 (and in the past five years it's been March 5).  This is four weeks earlier than what the average date was during 1869-1899; and during the 20th century this first occurrence was at the end of March.  The earliest date for a 70+ reading has been Jan. 6, which happened in 2007 (joining two other "first 70s" in January, in 1932 and 1950); the latest date is May 9, which happened in 1875 (and it's happened in May in five other years, the last time being in 1940).

 

Chart - earliest first 70s

Chart - latest first 70

 

The average high temperature on the day of the first 70+ has been 74°; the average low on that day, 48° (this diurnal variation of 24 degrees is much wider than the typical daily variation of 15 degrees).  The average high of the day before the first 70+ is 60°; the average high on the day following the first 70+ day  is 66°. 

 

11 years' first 70+ reading also served as those years' first 80°+ reading, with the most recent occurrence being in 2003.  And in 1927 the year's first 70+ served not only as the first 80+, but as the year's first reading in the 90s.  Meanwhile, 15 other years had their first 80+ come the day after the first 70+ (the last time this happened was in 2013).

 Chart - warmest first 70s

 

Back-to-back years with very early dates for the first 70+ are 1949 (Feb. 15) and 1950 (Jan. 26), and 2017 (Feb. 21) and 2018 (Feb. 24).  And there have been two periods of three consecutive years with very late dates: 1883 (May 3), 1884 (May 2) and 1885 (April 21); and 1875 (May 9), 1876 (May 6) and 1877 (April 23).

 

The greatest difference in high temperature between the day before and the day of the first 70+ is +34 degrees, in March 1935 (from 43° to 77°), and +33 degrees in April 2001 (from 45° to 78°).  And the biggest decline on the day after occurred in March 1934, -35 degrees (from 71° to 36°), and -34 degrees in Feb. 1874 (from 72° to 38°).  Lastly, the biggest increase on the day after is +14 degrees in 1902 (from 70° to 84°).

 

Chart - biggest temp diff day before first 70

 Chart - biggest temp drop after first 70

The greatest diurnal variation on the day of the first 70+ is 42 degrees, with a high/low on March 13, 1990 of 85°/43°.  The coldest reading to occur on the day of the first reading of 70+ is 30° on March 18, 1934.  It came after the high of 71° was reached and a cold front moved thru mid-afternoon.  (This is the also the only time a reading of 32° or colder occurred on the same day as the first 70°+.)

 

After a reading of 70°+, the average number of days before the next reading of 70°+ has been 11, with the greatest hiatus being 80 days in 1932 (when the first 70+ was on 1/14).  Not surprisingly, the most days to elapse before the next 70+ high have occurred in Jan/Feb -  with the average hiatus being 43 days.  In about one-third of the years, the first 70°+ was followed the very next day by another high of 70+, with the longest streak being eight days, in April 1896 (including highs of 87°, 88° and 90°).  The longest streak in the years since 1900 has been six, set in April 1952.  

 

Spring awakening
 

 

An early first 70+ isn't predictive of a hot summer as some very hot summers had their first 70+ at a late date.  This includes the year with the second hottest summer, 1966, which didn't see its first 70+ until April 25.  And the fifth and sixth hottest summers, in 1983 and 1993, didn't have their first 70+ until April 25 and April 19, respectively.

 

About 20% of the dates of the first 70+ reported measurable rain; two-thirds of these years had amounts less than 0.10".  (By contrast, 40% of the days with the first 60+ reading had rain.)  Just one date had more than an inch, on April 6, 1937.  On that day, 1.02" of rain fell before dawn and ushered in mild air (the high reached 72°).

 

And, finally, some more interesting occurrences:

> In 2018, after a high of 78° on Feb. 21 (the warmest reading ever in Jan/Feb), more than seven weeks passed before the mercury rose above the low 60s.

> In 1998 the first 70+ reading was 83°, and it was the first of five days in a row in the 80s - at the end of March (March 27-31), when the average high is in the mid-50s. 

> The first high of 70+ in 1988, 76° on 3/24, came just two days after a low of 17°

> The day of 1980's first 70+ followed a big rainstorm of 3.42" the day before.

> In 1967, a week after the first 70+, on March 11, there was a week of harsh winter conditions, with an average high/low of only 31°/20°, including a reading of 8° on 3/19; and three snowfalls produced 15.4" of snow. 

> 1947's first 70+ on 4/6 was the day after nearly two inches of rain fell. 

> In 1929 the first 70+ came three days after a low of 12°.  (In 2009 a low of 12° in March came four days before the year's first 70+.)

> In 1874, two days after a high of 72° on Feb. 23, 7.5" of snow fell. 

 

Springtime in central park

 

To read an analysis about the first readings of 60+ each year, double click here.

 

 

 


Central Park's Puzzling, Flawed Weather Station

Wtf 3This post has been a long time coming.  New York City, arguably the world's preeminent city, ironically, has a weather station in Central Park (serving as the official measurement site for NYC) that brings to mind that of a third world country.  There are regularly occurring instances of reporting glitches.  Last week, for instance, hourly sky conditions went missing.  (Looking out the window wasn't an option?).  This joined a host of other "irregularities": missing hourly precipitation/temperature reports (often during rainstorms); a five-month period in 2018-19 in which the anemometer was out of commission; a broken rain gauge that resulted in exaggerated amounts of rain for months in 1983; and flawed snowfall measurements in the winters of 2015 and 2016.

 

 

Central park weather site
Central Park's weather station at Belvedere Castle

 

The rain gauge fiasco occurred during a year that may have been the wettest on record as 80.56" was reported (16 inches more than the previous wettest year, 1972).  But it turns out that besides rain entering the gauge's calibrated opening, a faulty weld was allowing extra water to seep in.  Because of this malfunction, designating 1983 as the wettest year is questionable.  Although some cities in the mid-Atlantic did report their wettest year in 1983, confidence about 1983's amount in Central Park is lacking.  Like Barry Bonds' home runs, 1983 should have an asterisk placed next to it.  Meanwhile, 2011, which had 72.81", may actually be the legitimate wettest year.   

 

The revision of winter 2016's snowfall came nearly three months after the blizzard of Jan. 23, 2016.  At the time, the National Weather Service reported that 26.8" of snow had accumulated, which made it the City's second biggest snowstorm, 0.1" behind the blizzard of February 2006.  Then, curiously, the amount was revised upward by 0.7" in late April.  The previous winter the NWS revised New York's winter snowfall upward by 3.3" for three snowfalls.  Specifically, snowfall was adjusted on three dates: Jan. 6 (from 0.5" to 1.0"); Jan. 24 (from 2.5" to 3.6"); and Feb. 2 (from 3.3" to 5.0").

 

Frustrated_clip art
 

What makes this situation more frustrating is the fact that the metro area's three airports (LaGuardia, Kennedy and Newark Liberty) experienced none of these issues.  So what does this say about the Central Park operation?  A lack of trained employees?  A lack of enthusiasm by those manning the site (perhaps they're hired from the same pool of applicants as the DMV)?  Or, is it due to a lack of funding?  Whatever the reason, a city with the cachet of New York deserves better.

 

The greatest city in the world

 

 



 

 

 


July 2020 Is Seventh Hottest; Drought Eases Up

Seventh place

 

Following a June that was 2.3 degrees warmer than average, July 2020 was even more above average, +3.5 degrees, with an average high/low of 87.4°/72.6°.  The month's average temperature of 80.0° made it the seventh hottest July on record.  July records were set for mildest reading for coolest low temperature (67°) and the most lows in the 70s/80s (26).  Additionally, it joined eight other Julys with 14 or more highs of 90° or hotter.  Low temperatures were instrumental in placing the month so high in the rankings as it was third warmest in that category while the average high was ranked sixteenth.  Precipitation was also a significant story as the 6.58" that fell made this the wettest month of the year, so far, and the wettest of the 15 hottest Julys (July 2019 previously held that distinction).  Tropical storm Fay contributed a significant portion of the month's rainfall.

 

As mentioned above, July had 14 days with highs in the 90s, the most since 2010.  This included two five-day heat waves.  Despite the large number of hot days the heat wasn't overbearing as only one day had a high of 95° or hotter (96° on 7/6).  This was the fewest of any July among the 10 hottest.  However, there were nine days with lows of 75°+ (tied for fifth most of any July), including two in the 80s (the counterpart to high temperatures in the triple digits).  And of the six days with below average mean temperatures, just one of them had a low temperature that was cooler than average.

 

Highline during covid-19
.

After an exceedingly dry May and June, with both months reporting less than two inches of rain, July had 6.58", making it the wettest month so far this year (nearly double the combined rainfall of the preceding two months).  More than half of the rain was from tropical storm Fay on 7/10 (2.54") and a severe thunderstorm the evening of 7/22 that dumped 1.23" in an hour.  (Newark Airport, just 20 miles to the west, was much rainier, with 11.17" measured - its wettest July on record).

 

Chart - july 2020 top 10 julys

 

Finally, June and July 2020 were the seventh warmest June-July combination.  And the number of lows of 70°+ in June and July (37) tied June-July 2010 for the greatest number.  (37 is the  average number for an entire year.)

 

Chart - hottest june_july combos

 

Here are previous recaps of July from 2014 thru 2019:

July 2019

July 2018

July 2017

July 2016

July 2015

July 2014

  Tropical


 


A Look at New York City's Hottest Weekends of All Time

Waterskiing

 

On the one hand, if you work a Monday-Friday schedule and have access to a beach or pool, a hot weekend can be delightful.  On the other, if you don't have access to a body of water hot weather can be brutal, especcially if you have outdoor plans or a wedding to attend.  This summer, the weekend of July 18-19 had highs/lows of 91°/72° and 94°/77°.  Hot, yes, but far from the most torrid weekends of all time in New York.  This analysis looks at conditions in two ways - by mean temperatures and by high temperatures.  In order to qualify, both Saturday and Sunday had to have highs in the 90s or hotter and lows in the 70s or warmer. 

 

Looking at mean temperature, the two hottest weekends were Aug. 13-14, 1988 (highs/lows of 96°/79° and 99°/80°) and Aug. 8-9, 1896 (95°/79°, 98°/82°).   Last summer (2019) had the third hottest weekend, with highs/lows on July 20-21 of 95°/82° on Saturday and 95°/80° on Sunday.  Focusing on high temperatures reveals that the five hottest weekends are different from the top-five based on mean temperature, with the hottest occurring on July 3-4, 1966 (highs of 100° and 103°), followed by July 20-21, 1991 (100° and 102°).  These are the only weekends in which both days saw highs in the triple digits; four other weekends had one day of 100°+.

 

Hot weekend

 

And here are a few other findings of note. 

  • The earliest and latest scorching hot weekends occurred in the same year - 1895 (in the before-air conditioning era).  On June 1-2 the highs/lows were 96°/77° and 96°/76°; on Sept. 21-22 the highs/lows were 95°/77° and 95°/75°. 
  • Besides 1895, 1953 also had two sizzling weekends. The most consecutive summers with a hot weekend were in 1943, 1944 and 1945.

 

Chart - summer 1943 1944 1945

 

  • The weekend of July 20-21 has been very hot in three summers: 1957, 1991 and 2019.
  • Finally, the first weekend with lows in the 80s on both days occurred in 2019 (82° and 80°).  However, the weekend of July 23-24, 2011 had the warmest low of these select weekends - 83° on Saturday.

 

 Chart - 10 hottest mean temps in july

 

Chart - 10 hottest highs in july

 Scorching hot


Here are other heat-related posts:

Revisiting New York's Hottest Summers

"Super" Heat Waves (95°+)

Hot, Wet New York Summer

Low Temperatures of 70° or Warmer

The Heat is On: New York's "Hell Week"


June 2020: Warm & Dry

Hello summer2

 

June's temperatures rebounded after a chilly April and May (2.7 and 2.1 degrees below average, respectively).  At 2.3 degrees above average, it was the warmest June in 10 years (and 16th warmest overall).  Fourteen days were five degrees or more above average.  Besides being warmer than average, June was also on the dry side, with the least rainfall in 21 years (and 22nd driest overall).  The month had 1.76" of rain, which was very similar to May's 1.65" (like June, May was the 22nd driest).  This was just the sixth time (since 1869) that May and June both received less than two inches, and the first time that consecutive months had less than two inches of precipitation since April and May 2016 .  

 

Based on average temperature, June had the biggest warm-up following May since 2008.  And out of all of the years of measurement, it was the 12th biggest warm-up after May (tied with two other years).

 

Although the number of days of 80°+ was close to average (18, including the final twelve days of the month), it was well above average for days of 85°+.  13 days had highs of 85° or warmer, with 11 of them between 85° and 89°.  The two other days had highs of 90° (on June 22 and 28).  At one point there was a streak of seven days in a row with highs of 85°+, the longest streak in June since 2010.  Furthermore, the month's 11 days with lows in the 70s was more than double the average for June.  Only three other Junes have had more lows of 70°+ (2010, 2005, and 1943 had 12; June 1895 had the same number as June 2020).

85 plus
Through 6/26 it appeared the month would easily be among the ten driest Junes as just 0.98" had fallen.  Beginning 6/12 there were 15 days in a row with no measurable rainfall (the longest dry streak since the fall of 2017, which had a streak of 18 days).  Then 0.78" fell in the next three days.  The 0.58" that fell on 6/29 (in less than an hour) made it the rainiest day of June (and a wind gust of 47 mph was the highest of the month). 

 

Finally, the first half of 2020 was the driest since 1995 (16.15" was measured in Central Park, eight inches below average), and among all years it was the 17th driest first half of any year (tied with 1957).

 

Dry

 

Below are links for previous June recaps:

2019

2018

2017

2016

 

 

 

 

 

 


May 2020 Weather Recap - Chilly & Dry

Polar vortex of may 2020

 

May 2020 was 2.1 degrees below average, and followed an April that was also cooler than average (-2.7 degrees).  The last time back-to-back months had below average temperatures was in March and April 2018.  This was the chilliest May since 2008.  What made the month cooler than average was the 10-day period between May 5-14, which was nine degrees colder than average.  (The month's other 21 days were slightly above average.) 

 

The brunt of the extended cold period mentioned above was May 9, when the high/low was just 48°/34° (nineteen degrees below average).  The day's low reading was the coldest reported in May since 1891.  Previous to this May, the last one with a reading in the 30s was in 1978 (38°).  Lows were in the 30s for three consecutive days, May 8-10 - just the fourth May with a cold streak of this length, joining 1891, 1923 and 1947.  Besides the chilly air, snow flurries fell before daybreak, tying May 9, 1977 for the latest date with a trace of snow.

 

Cold in may
 

May was also a dry month.  With just 1.65" rain measured, this was the driest May since 2005 (and fourth driest since 1970, and 22nd driest among all Mays).  This amount was 60% below average (a deficit of two-and-a-half inches).  The wettest day was the Saturday of Memorial Day weekend when 0.65" was measured, with most of this amount pouring down between 11 AM and noon.  This was the rainiest Memorial Day Saturday since 1982.

 

Before the unseasonable Arctic outbreak of May 5-14, May began on the mild side, with the first four days four degrees above average.  5/1 snapped a 16-day streak of cooler than average temperatures; 5/2's high of 73° was the first reading in the 70s in more than six weeks; and May 3 saw the year's first reading of 80°+ - the first time since 2014 that a year's first 80 didn't occur in April. 

 

May's warmest reading, 84°, came six days after 5/9's frosty reading of 34°.  This was the first May since 2008 to have no readings of 85° or warmer.  (A typical May's warmest reading is in the upper 80s.)  The warmest mean temperature was on 5/29 and 5/30, both with a high/low of 81°/67° (eight degrees above average). 

 

Finally, there were a dozen days with lows cooler than 50°, double the average amount (since 2000) and the most in May since 2008. 

 

Here are recaps of the previous five Mays:

2019

2018

2017

2016

2015

 

 

 


April 2020 Weather Review: First Cooler Than Average Month of the Year

April 2020

 

April was 2.7 degrees below average, making it the first month this year to be chillier than average.  It was also the fourth chilliest April of the past 40 years.  Even more interesting, this was the first April since 1940 with no highs of 70° or warmer (after three such days in March).  In the years since 2000 the warmest reading in April has averaged 85°, but this April's mildest reading was just 68°.  Despite this cool warmest reading, the nights weren't as cold as might be expected as the coldest reading, 36°, was three degrees milder than a typical April's coldest temperature.  The 32-degree difference between the month's coldest and warmest readings was 20 degrees less than the average difference between the two extremes - the smallest gap of any April on record.

 

The last sixteen days of the month all had below average mean temperatures, the longest below average streak since March 2018's streak of 22 days.  These 16 days were seven degrees below average (seven of the days were ten or more degrees below average).  Before this streak started April had been two degrees milder than average (with April 4-8 seven above average).

 

Although it was the fourth coldest April of the past 40 years, it ranked 63rd among all Aprils going back to 1869.  This was due to the fact that Aprils before 1940 were much chillier.  (Six of the eight Aprils with no high readings of 70° or warmer occurred between 1873-1884.)

 

Cool-ish

 

Although April's rainfall, at 4.49", was an average amount, it was enough to make it the rainiest month so far this year.  The month also had the year's biggest rainstorm - 1.92" on 4/13 (the day after Easter).

 

A typical April is 10 to 11 degrees warmer than March, but April 2020 was just 2.4 degrees milder - the third closest of any year.  Additionally, April's mildest reading was nine degrees cooler than March's (68° vs. 77°) and its mildest low temperature was one degree cooler than March's (53° vs. 54°).

 

Chart - closest april-march temp
 

2020 is just the seventh year in which April, March and February had more precipitation than the month preceding it. This year April had 4.49"; March, 3.78"; February 2.54"; and January 1.93".

Chart - first 4 months of rain

 

Here are April recaps of previous years:

2019

2018

2017

2016

 

     


March 2020 Weather Recap - 8th Mildest on Record

Nyc-covidjpg

 

March 2020 was 5.5 degrees milder than average, becoming the eighth mildest March on record.  By coincidence, this  followed an eighth place ranking for February 2020.  Only one day had a low of 32° or colder (a typical March has twelve such days), occurring on the first day of the month when the mercury fell to 25°.  The month's warmest reading was 77° on 3/20.  For the third month in a row precipitation was below average, but the 3.78" that was measured was the most of the three months.  The year's rainiest and second rainiest days, so far, occurred on March 23 (1.19") and March 19 (0.93").  Like February, just a trace of snow was reported, only the second winter in which this occurred (the other winter was in 2002).

 

 Chart - 10 mildest marches

  Chart - least snow feb-mar

 

Here are previous March recaps:

2019

2018

2017

2016

 

 

 


February 2020 Weather Recap - Mild & Snow-Free

8th place

 

After a January that was the eleventh mildest on record, February ranked even higher, at #8 (and it was the third mildest Leap Year February, behind 2012 and 1984).  This was the third February of the past four to rank among the ten mildest.  But despite it being the mildest of this winter's months it had the coldest temperature of winter, 14° on 2/15.  (However, the coldest day of winter continued to be Dec. 19, which had a high/low of 25°/16°.)  In addition to being the seventh mildest February (4.8° degrees above average) it was the sixth February with no measurable snow (the last time was in 2002).  Other observations:

 

  • Similar to December and January, February had just one day with a high of 32° or colder (and each month had four days with highs of 35° or colder).  By comparison, a typical meteorological winter has a sixteen days with highs of 32° or colder.  Speaking of the winter, winter 2020 was the sixteenth to have December as the coldest of the three months.  And this was despite December's average temperature being slightly above average.
  • Three-quarters of the month's 2.54" of rain fell between Feb. 6-13.
  • After being nine degrees above average during the first thirteen days of the month, the rest of February had temperatures closer to the norm - two degrees above average.
  • Although it was milder, February had one more day with a low of 32° or colder than January.  Despite the month's mild temperatures just two days were in the 60s.  The highs on these days, 61° (on 2/4) and 62° (2/24), were not nearly as mild as January's mildest highs of 69° and 68°.
  • This was the driest January-February since 2009.  (February was the driest in three years, January was the driest in eighteen years.)  Jan-Feb 2020 ranks among the twenty driest first two months of a year.
  • After January missed by a small margin being the tenth mildest, February missed by an even tinier margin of being seventh mildest.

 

Chart - Jan Feb Photo Finishes

(If Leap Year Day hadn't been so chilly, with a high/low of 35°/25°, February 2020 would have finished as seventh mildest rather than eighth.)

 

Previous February recaps:

2019

2018

2017

2015

 

 

 

 

 


January 2020 Weather Recap: Mild, Dry, Largely Uneventful

Mild

 

January 2020 was the 11th mildest January on record (6.4 degrees above average).  Only six days had below average temperatures; just one had a high of 32° or colder, joining 10 other years with either no such days or one.  The month's highlight was the May-like temperatures during the second weekend of the month when record-setting highs of 69° and 68° were reached.  The coldest reading was 20°, which happened on three days (January's coldest temperature is typically around 9°).  Looking at precipitation, this was the driest January since 2002, with a little less than two inches measured (half the typical amount).  As for snowfall, only 2.3" was measured (but double last January's total).  

 

A typical January is five degrees colder than December, but January 2020 was 0.8 degrees warmer - the 31st time January has been milder than December; the previous time it happened was during the winter of 2006.  Besides being slightly milder than December, its snowfall was a touch less as well (2.3" vs. 2.5").  Although the month had a minimal amount of snow, there have been 36 Januarys with smaller amounts.  

 

Three consecutive Saturdays had very different conditions:  Saturday, Jan. 11 had the mildest reading of the month (69°); Saturday, Jan. 18 had the biggest snowfall (2.1"); and Saturday, Jan. 25 had the biggest rainfall (0.85").

 

Mild weekend in january
Basking in the springlike temperatures of Jan. 11
 
Record mild weekend january 2020
Temperature map during the very mild weekend of Jan. 11-12

 

The month began with a continuation of a streak of above-average temperatures that began on Dec. 22 and continued thru Jan. 8.  This 18-day streak equaled the longest above-average streak of 2018-19, which happened at roughly the same time of the year (12/20-1/6).  Then, after one day with below average temperatures, there were seven more consecutive days with above average temperatures.  The entire 26-day period from 12/22 thru 1/15 was ten degrees above average.

 

A streak of six days in a row with mean temperatures ten degrees or more above average (Jan. 10-15) was closely followed by six consecutive days with lows in the 20s (Jan. 17-22).  Although this was far from frigid, it equaled last winter's longest streak with lows colder than 30°. 

 

January continued the pattern of one month wet, the next month dry, a trend that started in September.

 

Chart - 5-month precip trend sept 2019-jan 2020

 

Finally, this January missed being among the ten mildest January's by the smallest of margins as it was 0.08° degrees chillier than January 1880 (39.15° vs. 39.23°).  And although January 1880 had two days with lows in the teens (both were 17° readings) and its warmest temperature was four degrees cooler than this year, it had five more days with highs of 50°+ (14 vs. 9).  Both years had nearly identical snowfall (2.3" in 2020, 2.5" in 1880) and precipitation (1.93" in 2020, 2.02" in 1880).

 

Here are analyses of the previous six Januarys:

2019

2018

2017

2016

2015

2014