DC’s Hottest Holiday

July is typically the hottest month of the year in the Nation’s Capital.  DC’s average high and low temperatures of 88°/71° on Independence Day make it the hottest holiday of the year.  Although no widespread rain is expected today, measurable rainfall has occurred on five of the last six July 4 holiday’s in Washington, D.C.  DC Area residents may recall the high of only 74° on July 4, 2016 combined with the 0.32” of rain that made it DC’s coolest and wettest Independence Day’s in recent memory. 

Average high and low temperatures in Washington, D.C. range from 88°/70° on July 1 to 88°/71° on July 31.  DC’s hottest July temperature is 106° that occurred on July 20, 1930.  That’s also the hottest overall temperature on record in the Nation’s Capital.  DC’s coolest July temperature is 52° that’s occurred three times, most recently on July 4, 1933.  Nine of the last 10 July’s have been warmer than average in Washington, D.C.

Five of DC’s 10 warmest July’s have occurred since 2010, including the three warmest.  July 2011 set a new record for warmest July with a monthly average temperature 4.7° above average.  Washingtonians saw a record seven days of triple-digit heat in July 2012.  Last July finished with 22 days of 90° heat and tied with 1955 for DC’s ninth warmest.  Washingtonians haven’t experienced a cooler than average July since 2014.

Seven of the last 10 July’s have been wetter than average in the DC Metro Area.  The Nation’s Capital averages 3.73” of rain in July making it DC’s third wettest month of the year.  That amount can vary quite a bit, however, depending on whether a tropical system impacts the Mid-Atlantic or if a thunderstorm occurs within city limits.  Washingtonians have set several daily rainfall records during the last two July’s.  For example, 4” of rain occurred on July 21, 2018, while 3.44” occurred on July 8, 2019. 

July was a very memorable weather month in the DC Metro Area during the 2010s.  Two of DC’s 10 wettest July’s have occurred in just the last three years.  July 2018 had 9.73” of rain and was part of DC’s wettest year on record.  Merely a year earlier, Washingtonians had 9.15” of rain in July 2017.  Last July was wetter than average with 6.49” of rain, but more than half of that occurred on one day.

DC is currently in the midst of a heat wave, currently at eight consecutive days of 90°/+ heat, with it expected to continue through the upcoming week.  NOAA expects July 2020 to be a warmer than average month in the Nation’s Capital with near average rainfall.