D.C. just matched its fourth-warmest April on record, but May is set to take on an entirely different character. A much chillier weather pattern is taking hold and was apparent from the start Friday. Many Washingtonians were greeted with morning lows in the frosty 30s to open the new month.
We project May will average 2 to 5 degrees below normal, with an average temperature of 62 to 65 degrees. For comparison, April’s average temperature — about 4 degrees above normal — was 62 degrees.
April marked the 10th month out of the last 11 with below-normal rainfall, with less than half the typical amount. We don’t expect May to be quite as dry, but it will probably still lean slightly below to near normal.
What models forecast for the month
All of the long-range computer models agree May will be chillier than normal in the D.C. area. They project the chilliest weather, with respect to normal, in the first two weeks and then suggest temperatures will return closer to normal in the month’s back half.
What this means is that highs in the first two weeks will frequently be in the 60s, rather than the more customary 70s. The beginning of May will also favor chilly nights, sometimes dipping into the 40s and even 30s in our colder areas, where some frost will remain possible.
By the second half of May, highs should more frequently reach the 70s or higher.
The models generally project near-average rainfall, with the next chance for meaningful amounts next Wednesday and Thursday. It’s unlikely enough rain will fall to put a meaningful dent in the area’s severe drought.
What’s typical in May and what’s more unusual
May is known for being one of the nicest months of the year in D.C., as average highs rise from the low 70s to near 80. Humidity is usually held in check and nights are comfortable, with lows in the 50s to start to the month and nearer 60 at the end.
But both chilly and uncomfortably hot weather happen, at times. Record highs throughout the month range through the 90s, while record lows are in the 30s to near 40. Freezing weather remains possible through about the third week, mainly in colder suburbs north and west of the Beltway. Washington Dulles International Airport’s latest last freeze occurred on May 22, 2002.
May is the third-wettest month of the year on average and often when thunderstorm season begins to kick into gear. Notably one of the big Ellicott City, Maryland, floods occurred on May 27, 2018, when about 8 inches of rain fell in three hours.
Recapping April
D.C.’s average April temperature this year of 62 degrees, 3.8 degrees above the norm, tied with 1981 and 1994 as the fourth-warmest on record. It was particularly warm during the first 20 days, as highs reached at least 80 nine times. Highs hit 90 twice, on the 15th and 16th, about a month ahead of what’s typical.
In all, highs reached at least 80 on 11 days during April, pushing 2026’s count of such days to 15, the most on record through April 30.
Temperatures did cool sharply to conclude the month. Seven of the past 10 days were below normal.
Precipitation was a major disappointment. Just 1.55 inches of rain fell, which is 1.66 inches below normal.
Capital Weather Gang accurately predicted the warm and dry month. On April 1, we projected the month would be 3 to 6 degrees warmer than normal, with rainfall 1 to 2 inches below normal. Both calls were spot on.
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