What Should DC Residents Expect?

Some consider the month of April to have the nicest weather of the year in the Nation's Capital. That's because average temperatures range from a high of 62° to a low 42° on April 1 and a high of 71° and a low of 52° on April 30.  Gone is the late-winter chill that often lingers well into March.

DC's hottest April temperature is 95°, which occurred three times, most recently on April 17, 2002. On the other hand, DC's coldest April temperature is 15° on April 1, 1923.  Since 2000, 16 of the last 20 April's have been warmer than average in the Nation's Capital, including nine of the last 10.  Part of that can be attributed to the significant urban heat island effect in the DC Metro Area.  That's largely the result of the increased construction and automobile traffic, which also curtails how cold it can get at night.

DC's official weather reporting site at National Airport on the Potomac River also influences temperature.  Areas on or near the water often see a moderating influence at night compared to areas away from a body of water.  At the same time, National Airport often remains a few degrees cooler during the day when a south wind is blowing off the water then nearby areas such as the National Mall.  Over the last two decades, the Nation's Capital has had a combined total of 18 record highs and record high-low temperatures, compared to only two record low and record low-high temperatures.

Washingtonians average 3.06" of rain during the month of April.  Twelve of the last 20 April's were drier than average in the Nation's Capital, including three of the last four.  April snowfall has occurred in the Nation's Capital, but has become increasingly rare.  DC's biggest April snowfall remains the 5.5" from April 1, 1924.  Meanwhile, the latest accumulating snowfall occurred in the Nation's Capital was April 28, 1898 (0.5").

The DC Metro Region typically sees an uptick in the frequency of severe weather in April.  For example, DC's first tornadoes since 1995 occurred within city limits on April 6, 2017.  Longtime residents may also recall that Maryland's strongest tornado on record occurred on April 28, 2002, when an F4 tornado decimated the town of La Plata in Charles County.  An F4 tornado in 2002 would be ranked as an EF5 today with winds over 200 mph since the Fujita Scale was updated or "enhanced" in 2007.

Although April 2020 got off to a chilly start on Wednesday with highs in the 50s, temperatures rebounded yesterday to reach a near average high of 63°.  My colleagues and I on the WUSA9 Weather Team are also tracking a moderating trend with temperatures poised to reach the upper 60s by early next week.  NOAA's monthly outlook is for above average temperatures and near average April precipitation in the DC Metro Area.