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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

 

 

 


May 2019 Continued April's Wet Trend, But With More Rain

Cold-rain-and-wind-bear-down-on-new-york-city-commuters-20190513081420-84079800Like the month preceding it, May 2019 was characterized by a surfeit of rainy days.  There were 19 with measurable rain, which tied December 1972 and May 1973 for the second greatest number for any month.  (The most days, 20, occurred in July 1871 and May 1888).  However, May 2019 distinguished itself by having more rain than those other months (see chart below).  The amount that fell, 6.82", made this May the 12th rainiest on record.  Although it had one more day of rain than April (its 18 days was a record for April), nearly two-and-a-half inches more rain fell.  But despite the high frequency of rain, much of it occurred on just five days: 1.31" on 5/5; 1.32" on 5/12; 0.70" on 5/13; 0.80" on 5/29; and 0.95" on 5/30.

 

Chart - 5 months with most days of precip
 

In addition to the well above average number of rainy days, this May will also be remembered for the damp and unusually cool conditions on Mother's Day and the two days after.  2.32" of rain fell on these three days (1.32" of it on Mother's Day) and the average high/low of 53°/43° was 14 degrees cooler than average.  By contrast, the Memorial Day weekend was mostly nice,  the exception being later in the afternoon on Sunday when clouds moved in and there was an hour of heavy showers.  The three-day weekend's average high/low was 79°/60°, four degrees above average, and featured the warmest reading of the month, 86° on Sunday.  (The warmest mean temperature, however, occurred on 5/20, one week before Memorial Day, with a high/low of 85°/66°).

 

Temperature-wise, the month was average (officially, 0.2 degree below average), with the first half of May three degrees below average while the second half was two degrees above average.  (If the chilly three-day period from May 12-14 were taken out, the month would have been 1.3 degrees milder than average.)  Seven days were five or more degrees above average while six were five or more below average.  Four days with highs in the 80s were balanced by four days with lows in the 40s, both fewer than the month's average (of seven and six days, respectively). 

 

Finally, there was an eight-day streak of rainy days (May 10-17) that had 2.56" of rain.  This was just the thirteenth eight-day steak since 1900.  Coincidentally, last May had rain on seven of eight days around the same time of the month (May 12-19), which amounted to 2.14".  And Mother's Day both years was cool (59°/43° this year, 54°/52° in 2018).

 

Here are recaps of the previous four Mays:

2018

2017

2016

2015

 

 


Comparing High Temperatures on Mother's Day and Father's Day

Fathers day and mothers day

 

Since Father's Day is about five weeks later than Mother's Day its high temperature is, on average, about thirteen degrees warmer (82° vs. 69°).  However, in 2018 there was a huge disparity in the temperatures as Father's Day had a sizzling high of 91° while Mother's Day's was only 54°.  This 37-degree difference tied 2010 for the greatest difference in temperature between the two holidays (and there was a 36-degree difference in 1994).  However, not every Father's Day has been warmer.  Since 1960 there have been eight Mother's Days with warmer highs (most recently in 2014), with the greatest difference being 28 degrees in 1970.  And sometimes the two holidays have similar readings; for example, in 2000 and 1974 they had the same high temperature.

 

Mothers Day Fathers Day

 

 


May 2018 Weather Recap - Big Rebound From April

Month of mayAfter suffering through the chilliest April in more than 40 years May reversed course and ranked among the ten warmest, ranking sixth (4.5 degrees above average).  The month's unseasonable warmth began right out of the gate as May 1 saw a high of 80° followed by back-to-back days with highs in the 90s.  This was one of the warmest beginnings to May on record (see chart below).  There were also three days later in the month with highs of 88° (5/17), 89° (5/26) and 89° (5/29).  The last time May had five days with highs of 88° or hotter was in 1991 (which was the warmest May on record). 

 

After the three previous months each had more than five inches of precipitation, May was drier than average, with 3.55" of rain measured.  However, there was a period in which seven days out of eight had rain (May 12-19); this included a severe thunderstorm on 5/15 that moved through during the evening rush hour (five people in the metropolitan area were killed by falling tree limbs).

 

Twelve days had highs of 80° or warmer, eight days were 10 degrees or more above average and three days had lows in the 70s.  And although May 2 and 3 had highs in the 90s, the most uncomfortable day was May 26, which had a heat index of 93° (its high was 89°).  By contrast, May 2 and 3 had very low humidity and their "feels like" temperatures were lower than the air temperature.  Only six other Mays have had three or more lows in the 70s (since 1930), with two of them being in 2016 and 2015.

 

Balancing the two days in the 90s were two days with highs in the 50s - May 13 (Mother's Day) had a high of 54° and May 19 had a high of 56°.

 

Last May was just 3.9 degrees warmer than April, the second closet the two months have been  (closest was 3.5 degrees in 1945).  By contrast, this May was 17.4 degrees warmer than April, the seventh furthest from April (furthest was 18.1 degrees in 1944).  May is typically 9.3 degrees warmer than April.

 

Chart - warmest starts to May 

 

Here are links to recaps of previous Mays: May 2017, 2016 and 2015.

 


May 2017 Recap: Cooler Than Average Despite Three 90-Degree Days

MayAfter experiencing its second mildest April, May in New York was cooler than average.  Despite this cool down, it had three days in the 90s, the first time that's happened in May since 2001.  These  days were consecutive, from May 17-19, with highs of 90-92-91.  However, what made the month unique was the fact that it was the first May to have 90-degree days - but no days in the 80s.  It was also the coolest of any May that had three or more 90-degree days (see chart below).  Overall, the month was 1.3 degrees cooler than average, making it the coolest May in nine years.  Interestingly, despite the 90-degree days, what made the month below average was its average high temperature, which was 2.6 degrees below average; the average low, however, was in-line with the 30-year average.

 

May 2017 Weather


FURTHER OBSERVATIONS

  • After the three-day heat wave ended on 5/19, the remaining twelve days of the month had an average high of just 67° (with highs on four of the days in the 59°-61° range).  Only six days all month had an above-average daily mean temperature.  (Without the month's three 90-degree days, the average high would have been five degrees below average.)  Memorial Day, with a high of 61°, was the coolest since 2003 (temperatures in the afternoon were only in the upper 50s).  And although Mother's Day was somewhat cooler than average, it was milder than Memorial Day (high of 67°).
  • A typical May is 9.4 degrees warmer than April, but this year it was just 3.9 degrees milder.  Only in 1945 was May's average temperature closer to April's (a 3.6-degree difference).
  • The rainstorm of 5/5 flooded the City with 3.02" of rain, a record for the date.  Most of it poured down in a three-hour period between 11AM and 2PM.  This was New York's biggest rainfall in three years, and May's fifth biggest daily rainfall total (tied with a storm on May 8, 2013).  Eight days later another significant rainfall soaked the area, with 1.61" measured, but unlike 5/5's deluge, this storm's rain fell for an extended period, from daybreak until midnight.  The day's amount was just 0.05" shy of the record for the date.  In total, 6.38" of rain was measured in Central Park during May, making it the wettest May since 2013, and second wettest of the 21st century (and fifteenth wettest among all Mays).  The rainstorms of 5/5 and 5/13 accounted for nearly three-fourths of the month's rainfall.

 

May 5 deluge
A view of the May 5 deluge from my office.

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Other May recaps from previous years:

May 2016

May 2015

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As Seen on TV ...

Pix11On occasion I've been asked to provide my point of view about weather events on New York TV station WPIX.  PIX-11 news reporter James Ford came across my blog back in 2014 and has contacted occasionally to get my historical perspective on weather conditions.  (What's made it easier for both of us is the fact that PIX's office is conveniently down the street from my office on 42nd St.)  Here are the nine appearances I've made (so far) including links to each :   

 

 

Revised.wpix
Nov. 10, 2014.  In my first appearance I was asked to comment about an approaching Arctic front that would drop temperatures to more than 10 degrees below average between the 13th and 22nd. At its coldest, the high/low on Nov. 19 was 36/22, eighteen degrees below average.

 

Rob.frydlewicz.wpix.jan8
Jan. 8, 2015. Talking about another Arctic air mass (which had me wearing earmuffs).

 

RobFrydlewicz_deepfreeze_pix11
Feb. 16, 2015. Here I am in front of my apartment building (it was President's Day) commenting about the coldest February since 1930.  As you can tell by the pained expression on my face, it was very cold, with a wind chill of 5° below zero at the time of the interview.

 

8.me on tv
May 6, 2016.  Commenting about the cool, damp and overcast conditions during the first week of May.

 

Me again on tv
July 22, 2016.  And here I am in front of Penn Station (my train to Lancaster, PA was leaving in 15 minutes) giving my perspective about a heat wave that I thought was over-hyped.

 

 

Me on pix
March 14, 2017 - I was asked to comment about the snowstorm that brought "only" 7.6" of snow rather than the 12-18" that was predicted (the storm produced a lot of sleet) and on the admission by the National Weather Service that it knew this was going to happen but decided not to lower snow totals.

 

Pix interview july 13
July 13, 2017 - On the 40th anniversary of the Blackout of 1977 I was asked to provide some perspective about the heat wave that coincided with the event (which was one of the City's most intense).

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Rob frydlewicz on pix-11 jan 30 2019
Jan. 30, 2019 - After an 18-month absence I was asked to comment about an approaching Arctic front. Shortly after this interview a blinding snow squall its arrival and the temperature plummeted from the low 30s to 6° above zero by midnight.

 

 

August 2019 on pix
Aug. 19, 2019 - On the second day with a high of 90° and dew points in the low-to-mid 70s, I was asked to comment on the hot weather. As I've said before this was far from the heat waves we had in 2010, 2011 and 2012. However, it's the warmer nights that were worthy of note. 

The Three Faces of May 2016's Weather

May2016WeatherRecapAfter experiencing our second mildest May on record in 2015, May 2016 came back down to earth with temperatures that were close to average (+0.4 degrees).  However, this masked three distinct temperature trends during the month that brought to mind the story of Goldilocks and the Three Bears.  The first week of May had temperatures more like the first week of April (too chilly), the last week of May had temperatures more like the month of July (too warm), while the middle two weeks had temperatures one expects for mid-May (just right). 

 

 

The first week of May was overcast, damp and chilly with temperatures that were 7.5 degrees below average - but it was the high temperatures that were affected most, at twelve degrees below average as temperatures never rose above 60°.  The middle two weeks were close to average, with ups and downs cancelling each other out.  The chilliest reading of the month occurred during these two weeks, 43° on 5/16.  But there were also four days with highs of 75° and higher.  Then the last week of the month brought back memories of last May, with the mean temperature 12 degrees above average.  Every day had a high of 82° or warmer, including two days in the 90s.  And four of the days had lows in the 70s.  The week's average high/low was 87/69.

 

May 2016 Weather Review

 

While the first week had no sunny days, the last week had no cloudy days.  But, ironically, the month's biggest rainstorm occurred in this last week, during the wee hours of Memorial Day, when 1.65" fall between midnight and daybreak; nearly one inch fell in just half an hour (12:30-1AM).  This was more rain than fell in either April (1.61") or March (1.17") and was the most precipitation from one storm since the big blizzard on Jan. 23.  And although this pre-dawn storm made it the second rainiest Memorial Day on record, the afternoon turned sunny and the high got into the 80s - the tenth Memorial Day of the past eleven to have a high in the 80s (average high temperature in late May is in the mid-70s).       

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

May2015After 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.

 

Warm.may

 

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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Cold, Raw Days of Late May

Grayday.newyorkA few weeks ago I published a post about warm weather in May.  Most of us are delighted to get an early start to summer with days that have temperatures in the 80s and 90s, especially because they aren't usually accompanied yet by the humidity levels common to mid-summer.  Of course, most Mays still have a few cool days in store to remind us that we're still transitioning from spring to summer (May 2015 was an exception).  And raw days in the latter part of May are especially cruel with summer so close at hand.  This post focuses on these late, cold days.

 

Two dates that stand out on the list below are May 26, 1967 and May 27, 1961.  Both had highs only in the 40s, which is what the typical high is in the second week of March.  The high on May 26, 1967 was 46°, twenty-eight degrees below average; May 27, 1961's high of 47° was twenty-seven degrees below average.

 

One characteristic of chilly days in May is that high temperatures are often significantly more below average than low temperatures.  This is due largely to clouds and rain (and north-northeasterly winds).  Although a typical day in May has a 15-degree difference between its high and low, the chilly days listed below show diurnal variations that are often half that range (seven degrees or less).

 

Clipart_drizzle_cloud 

 

CHILLY DAYS IN LATE MAY (SINCE 1915)
(Sorted by Calendar Date)
        Below Average
Date High Low Mean Mean High
5.20.2000 51 46 48.5 -15 -20
5.20.1957 51 45 48.0 -16 -20
5.20.1952 54 50 52.0 -12 -17
5.21.1990 51 47 49.0 -15 -20
5.21.1929 50 45 47.5 -15 -20
5.21.1924 50 47 48.5 -14 -20
5.23.1982 55 51 53.0 -12 -18
5.24.1982 55 50 52.5 -12 -18
5.24.1927 51 49 50.0 -15 -21
5.25.2013 54 45 49.5 -16 -20
5.25.2005 53 48 50.5 -15 -21
5.25.1967 46 42 44.0 -21 -28
5.25.1934 56 49 52.5 -11 -16
5.25.1925 53 41 47.0 -17 -20
5.25.1921 52 47 49.5 -14 -22
5.26.1967 55 42 48.5 -17 -19
5.27.1961 47 41 44.0 -22 -27
5.28.1917 55 49 52.0 -14 -18
5.30.1953 56 50 53.0 -14 -19

 

 

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Warm Weather in May

Weather.central_park_summertimeThe 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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