May Temperature Extremes

NOAA expects a cooler than average May for the Great Lakes Region and New England

Today will be the warmest day for the rest of the week with highs in the mid to upper 60s.  While still below DC’s average in the low 70s, it will still feel nice after two days of high temperatures in the 50s.  That’s more like March than the first full week of May.

Temperatures are going to be below average in the DC Metro Area for the next seven to 10 days.  Some record low-high temperatures will be threatened, specifically this Saturday, May 9.  What that means is that high temperatures are expected to remain appreciably cooler than the daily average high, which for May 9 in Washington, D.C. is 74°.

The last time DC residents experienced a record low-high temperature during the month of May was in 2003.  May 2003 was an unusually cool and rainy month, which saw three record low-high temperatures tied or broken.  Before this week, the last time high temperatures remained below 60° in the Nation’s Capital in May was in 2017.  On the opposite end of the spectrum were May 2018 and May 2019, which each saw four days in the 90s, including three consecutive days that made for a “heat wave.”  

NOAA’s Climate Prediction Center expects this month to be more like May 2017, which finished cooler and wetter than average.  There have already been two days this month with high temperatures in the 50s.  This weekend is setting up to be especially cold in the Nation’s Capital with low temperatures in the 30s for much of the DC Metro Area on both Saturday and Sunday mornings. 

A cold rain returns to the DC Metro Area on Friday afternoon and it could end with a few snowflakes early Saturday morning in areas north and west of town like Leesburg, Virginia and Clarksburg, Maryland.  The latest in the season snow has fallen in the Nation’s Capital was when a trace occurred on May 10, 1906.  The last time Washington, D.C. dipped below 40° in May was on May 3, 2005 when it was 38° at National Airport.  Having such unseasonably cold May weather is particularly hard to imagine since four of DC’s 10 warmest May’s have occurred just since 2012.  Whether or not any snowflakes fall in the DC Metro Area late Friday night / early Saturday morning, conditions will be ideal for patchy frost both Saturday and Sunday mornings.

This helps illustrate how streaky May weather can be in the Nation’s Capital.  Seven of the 10 May’s between 2000 and 2009 were cooler than average in Washington, D.C., while eight of the following 10 through 2019 were warmer than average.  If May 2020 finishes cooler and wetter than average month, then that would make 2020 the first year the Nation’s Capital has had both a cooler and wetter than average April and May since 2003. 

Record Low-High Temperatures (Source: NOAA)

May 9:

Washington, D.C., National Airport (DCA): 52° (1877)
Dulles Airport, Sterling VA (IAD): 55° (1977)
BWI Airport, Baltimore, MD: 53° (1977, 1947)