Quick Facts:

	Ave	10Y	Low (year)	High (year)
HLA	78.80	76.62	73.29 (2021)	82.06 (2022)
Highs	95.38	95.20	90°F (2015)	101°F (2011)
Lows	52.85	51.10	42°F (2013 & 2014)	62°F (2022)
Precip	5.28”	5.10”	0.02” (2010)	11.11” (2015)

 

 

May Temperatures

May’s 10-year temperature average is 76.62°F, ranked warmer than October but cooler than September. (However, the warmest Mays might be warmer than the same year’s September, and the coolest Mays are sometimes cooler than the same year’s October.) May 2022 is the warmest May on record, with a high-low average of 82.06°F (beating May 2018, which beat 2012, which surpassed May of 2010). I couldn’t find when the coldest May was, but the coolest recent one was in 2021, averaging 73.29°F.

According to a variety of sources I searched, the coldest temperature ever recorded in May was 42°F, once each in 2011, 2013, and 2014, while the warmest temperature May has ever seen was 101°F, thrice in 2011 (May 25, 28, and 29). In my 13 years of record-keeping, we have seen fourteen daily record highs broken, compared to only nine daily record lows.

May is the earliest month that sees 100°F days, though it’s rare — of the past 13 years, only 2011 experienced this (four days in the final week of May crested 100°F, each one setting a record for its respective day). However, every May in the past 10 years has seen 90-degree days — as few as one in 2015 and 2021 to as many as twenty-one in 2022. We average about 10.5 days per May that reach 90°F or higher. Notably, May’s number of 90-degree days is a very good predictor for June’s number: if May is above average, then June will be too (90% of the time).

 

 

Precipitation

Rainfall in May varies from 0.02 inches (in 2010) to 11.11 inches (2015), but averages 5.1 inches per May — the wettest month of the year. The only detectable pattern is similar to April’s: only one of the first five years was above average, while most the years since then have been. In other words, May has gotten wetter over the past decade years.

May averages 13 days per month that exhibit precipitation, the most of any month. The maximum was 25 days (2012) — the most rainy days of any month in the past 13 years. The minimum was two (2010).

 

Trends And Patterns

In the 13 years I’ve been keeping track, May’s temperatures do not seem to follow any pattern, nor are May’s temps a good predictor for the year as a whole. Further, there seems to be no correlation between temperature and rainfall. May’s rainfall also does not correlate with the yearly averages.

For the most part, May’s precipitation IS a good predictor of the year, in that if May is above average, so will the year be. (2018 was an exception to this.)

Both May’s temperatures and its precipitation are relatively good predictors of June’s numbers.

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