April Temperature Extremes

NOAA's Temperature Outlook for Later in April

Yesterday marked Washington, D.C.’s third day of 80 degree warmth so far this month.  Such warmth is more characteristic of June than the first half of April.  Most Washingtonians are eager for the warmer weather of late spring, especially considering how chilly April can be.  Average high and low temperatures in Washington, D.C. range from 62/42 on April 1 to 71/52 on April 30.

Dating back to 1993, Washington, D.C. has averaged three or four April days with temperatures in the 80s.  So having three so far this month puts us right at that mark.  Temperatures in the Nation’s Capital have reached the 80s at least once in every April since 1999.  Ironically, the last April Washington, D.C. didn’t experience 80-degree warmth was in 1998, while March that year ended with a streak of 80-degree warmth on 4 out of 5 days.

Much less frequent than April 80-degree warmth in the Nation’s Capital are 90-degree temperatures.  Since 1993, there have been only 10 days at or above 90 degrees.  There hasn’t been any 90-degree heat in Washington, D.C. in the month of April since 2013.  The earliest in the year that the thermometer has reached 90-degrees in Washington, D.C. was March 22, 1907.  

Some longtime DC residents may recall the April heat wave that occurred in 2002.  A “heat wave” is defined as a minimum of three consecutive days at or above 90 degrees.  That’s exactly what Washingtonians experienced from April 16-18.  April 17, 2002 is the most recent of four times Washington, D.C. has experienced its hottest April temperature of 95 degrees.

Some may also wonder how common temperatures at or below freezing are during the month of April in Washington, D.C.  According to records kept by NOAA, temperatures at National Airport have been at or below freezing 14 times in April dating back to 1993.  That includes three times in April 2016.  However, temperatures have been below 30 degrees only twice in the Nation’s Capital during the month of April in the last 24 years.  Temperatures at or below freezing in April are only slightly more common than 90-degree heat is in Washington, D.C.  National Weather Service data indicates the last time measurable snowfall occurred in Washington, D.C. in April was on April 7, 2007 (0.4”).

NOAA’s current temperature outlook is for above average temperatures to continue over the next one to two weeks across much of the central and eastern United States. 

Strongest Mid-Atlantic Tornadoes

Severe Weather Reports for April 6, 2017 (Source: NOAA)

This past Thursday, April 6, was an historic weather day for the Mid-Atlantic Region since Washingtonians saw their first tornadoes in more than two decades.  Prior to this week, there had only been eight tornadoes on record in Washington, D.C. with the most recent on September 24, 2001.  Since official tornado records kept by NOAA began in 1950 and seven of the eight prior tornadoes in Washington, D.C. occurred before then, there is an inherent amount of uncertainty in the official count.

Last Thursday afternoon was historic because two EF-0 tornadoes touched down.  They caused only minor damage and, fortunately, no fatalities.  However, they were significant since tornadoes are very rare in the Nation’s Capital and these occurred as part of a larger severe weather outbreak.  From April 4 through April 6, a total of 550 reported cases of severe weather occurred from the Midwest to the East Coast, including 30 tornadoes.  

The United States sees most of its severe weather during the months of April, May and June.  True to form, five of the previous eight tornadoes to occur in the Nation’s Capital occurred during that timeframe.  The strongest tornado on record in Washington, D.C. was an F3 that developed in Rock Creek Park on April 5, 1923.

Maryland has had three significant tornadoes in the last 20 years.  On April 28, 2002, an exceptionally rare F4 tornado developed in Charles County.  Although this tornado had a track that spanned nearly 70 miles, it reached its peak intensity as it passed through the town of La Plata with winds of nearly 260 mph.  It caused a total of more than $100 million in damage, in addition to five fatalities and dozens of injuries.  The 2002 La Plata tornado remains the strongest tornado on record in the state of Maryland.

The town of College Park, Maryland saw a F3 tornado on September 24, 2001.  Tragically, two sisters who were students at the University of Maryland lost their lives during this tornado, which also caused extensive damage.  In addition, an F4 tornado occurred on June 2, 1998 in Frostburg, Maryland. Wind speeds of the Frostburg tornado were estimated as high as 210 mph.

NOAA data indicates the state of Maryland sees an average of 10 tornadoes annually, while the state of Virginia sees 18.  As in Maryland, the two strongest tornadoes on record in Virginia were F4s.  One occurred on August 6, 1993, and the second on September 24, 2001.  Tornadoes are ranked on the “Enhanced Fujita Scale” or “EF” scale for short.  Named after the late Dr. Ted Fujita of the University of Chicago, a scale to measure tornado intensity has been in use since 1971.