DC's May weather extremes

 

Avenel Pool, Potomac, Maryland (May 2023)

The nation’s capital will finish with its second cooler and drier May in the last four years along with 2020.  Not only has this May been drier than average but it’s poised to finish as one of DC’s top 10 driest on record. 

This May being drier than average is significant for a few reasons.  Not only have drought conditions developed in parts of the DC Metro Area, but this month’s dry weather has continued the dry trend that dates back to last August. 

Only 0.43” of rain has occurred so far this month at National Airport.  That would make this month DC’s second driest on record if no more rain were to occur.  It would also be the first time since 1986 that less than an inch of rain fell in Washington, D.C. during the entire month of May.  May 2023 could also finish as DC’s driest overall month since September 2019 (0.25”). 

DC’s rainfall deficit since January 1 is 6.19”.  And going back to last August, the rainfall deficit is even larger at 6.49” through April 30.  Beneficial, but scattered showers and light rain will occur over the next few days in the nation’s capital.

The warmest temperature so far this month in the nation’s capital is 85° on May 12.  That would make this May only the third over the last decade that no 90° heat has occurred.  Washington, D.C. has averaged between one and two May days in the 90s over the last 30 years based on NOAA data.  The nation’s capital typically sees its first 90° temperature of the year on or around May 18.  Washington, D.C. had two 90° days last May. 

However, 90° heat in May doesn’t correlate to a hotter than average summer.  For example, the first 90° heat of 2016 didn’t occur until June 11 and that went on to become DC’s third hottest summer on record. 

NOAA’s outlook for the next three months is for warmer and wetter than average weather conditions in the Mid-Atlantic Region.  That would be a welcome turn of events considering how dry it’s been in recent months.