Early Season Heat

DC residents experienced a record-tying high temperature of 83° this past Friday, March 20.  It was DC's warmest March day since it was also 83° on March 23, 2012.  You have to go back more than a decade to find the last time it was warmer than that: 85° on March 13, 2006.

As warm as those temperatures were, DC's warmest March temperature of 93° occurred on March 23, 1907. In fact, Washingtonians experienced three sweltering March days in the 90s back in 1907. Since they didn't occur consecutively, it didn't qualify as a "heat wave."

National Airport has been DC's official weather reporting site since it opened in the early 1940s. Prior to that, DC weather observations were made downtown since record keeping began in 1871. The key difference between making weather observations downtown vs. National Airport is the proximity to the water. The Potomac River, like all bodies of water, has a large influence on temperature at locations along the shore. National Airport is a great example of this because a south wind blowing off the chilly waters of the Potomac during the early spring will keep temperatures cooler than nearby areas away from the water.  The warmest March temperature on record at National Airport is 89° from March 12, 1990.

Washington, D.C. was largely rural and undeveloped in the early 1900s, but temperatures still got quite hot on occasion, as was evidenced in March 1907.  However, that month didn't rank among DC's Top 20 warmest March's.  The increased urbanization and automobile traffic that’s occurred in recent decades has helped make many urban areas warmer than they used to be.  One of the ways that’s manifested itself has been in the significant number of warm overnight low temperatures.  It isn’t possible to cool off at night as much as it used to be when the DC Area was less developed. 

DC has had nine record high-low temperatures during the month of March since 2000 as measured at National Airport.  Three of DC's 10 warmest March's have occurred just over the last decade.