Father’s Day Heat

Today will mark the first day of the second heat wave of 2018 and the first since early May.  A “heat wave” is defined as a minimum of three consecutive days with high temperatures of at least 90°.  Record breaking heat is expected in the D.C. Metro Area tomorrow, as temperatures reach the mid-to-upper 90s.  Although not typically as hot as July and August, Washingtonians have experienced some extreme heat in June in recent decades.

Washington, D.C. has averaged nearly eight June days with 90° since the early 1990s, according to the National Weather Service.  In that time, there has been an average of one heat wave lasting between four and five days.  D.C.’s two hottest June’s on record occurred in 1994 and 2010.  Washingtonians experienced a total of 17 days in the 90s in June 1994, including a streak of 14 consecutive 90° days (which marked the longest heat wave of the entire 1994 summer).  By comparison, June 2010 featured 18 days of 90° heat, including an 11-day heat wave.

There have been other June heat waves in the last 25 years that have featured high temperatures of at least 95° in Washington, D.C.  The most recent one occurred on June 28 – June 30, 2012.  Extreme heat, much like extreme cold, is unlikely to occur for extended periods of time.  That’s why high temperatures of 95° or more are rare and rarer still on consecutive days.

D.C. residents also experienced 100° heat in June 1994 and June 2010.  The last time Washingtonians experienced triple-digit June heat was on June 29, 2012.  That’s an important date to remember since temperatures will approach 100° tomorrow afternoon in parts of the D.C. Metro Area.  The Nation’s Capital averages one day of triple-digit June heat roughly every five years, so area residents are due for it.

Despite the very hot weather underway on this Father’s Day, the first half of June 2018 has actually been a very comfortable month in Washington, D.C.  Through June 16, this month’s average temperature (combining daily high and low temperatures) has been only 0.1° warmer than average.  There have been more days so far this month with high temperatures in the 70s (four) than high temperatures in the 90s (one).  However, that will change today with high temperatures in the mid to upper 90s for the D.C. Metro Area.  The Nation’s Capital hasn’t had temperatures of 95°/+ since July 22, 2017.

Record Highs

June 17:

Washington, D.C., National Airport (DCA): 97° (2014)
Dulles Airport (IAD), Sterling, Virginia: 92° (1994)
Baltimore, Maryland (BWI Airport): 96° (1939)

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June 18:

DCA: 97° (1944)
IAD: 94° (occurred most recently in 2007)
BWI: 97° (occurred most recently in 1957)

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June 19:

DCA: 99° (1994)
IAD: 98° (1994)
BWI: 99° (1994)