Warmest and Driest February?

This month will finish as the warmest February and among the driest on record in the Nation’s Capital.  In addition to the slew of record highs that have been set this month in the DC Metro area, Washingtonians have experienced 70-degree warmth in both January and February for the first time since 2008.  

Much to the chagrin of snow-lovers in the Nation’s Capital, February had the second highest total number of days in the 70s on record with six.  That’s just behind the 1976 record of seven days, which holds the existing record for warmest February in Washington, D.C.  How is it possible for this month to be warmer with fewer 70-degree days?  That can be explained largely by warmer overnight low temperatures this February compared to 1976.

There has been a lot of urbanization and development in the DC Metro Region since the 1970s, which enhances the “urban heat island effect.”  That helps keep temperatures warmer at night than in a more suburban or rural areas.  There were only eight days with temperatures at or below freezing this month in the Nation’s Capital.  That’s compared to a total of ten days with high temperatures of 60 degrees or warmer.

National Airport set two record high temperatures this month as well as four record high-low temperatures.  No measureable snowfall occurred in Washington, D.C. this February for the first time since 2004.  Meanwhile, Dulles Airport experienced similar conditions this month with three record highs and five record high-low temperatures.  In fact, the high temperature reached 77 degrees at Dulles on three consecutive days starting February 23, while it was only 77 degrees once this month at National Airport.  Such temperatures are more characteristic of Memorial Day than President’s Day.

National Weather Service data shows that the 2016-2017 winter (defined as the months of December, January and February) is poised to finish as the third warmest winter on record in Washington, D.C. – and warmest since 1931-1932.  This winter will likely be the warmest on record at Dulles Airport.  

Whether this month finishes as the first or second driest February is less important than the fact that the Nation’s Capital has an ongoing rainfall deficit of 13.27” dating back to August 2015.  There has been below average monthly rainfall in 15 of the 18 months since then, with a rainfall deficit of 2.69” just since December 1, 2016.