Cold, Raw Days of Late May
Early Summer Heat Waves in June

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.   


(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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