August Reaches Its Midway Point

The first half of August 2019 has been unremarkable in the Nation’s Capital.  It has been warmer and drier than average month.  Measurable rainfall occurred on three days so far this month, as compared to eight of the first 15 days of August 2018.  There has been 1.22” of rain so far this month in Washington, D.C. (0.28” below normal). 

What’s accentuated these dry conditions are the warmer than average temperatures.  There have been nine days with high temperatures in the 90s since August 1.  Only two days so far this month have been cooler than average.  That was this past weekend when high/low temperatures downtown were in the mid-80s and mid-60s, respectively.  Washingtonians looking forward to fall were thrilled with the sneak peek of more September-like weather.

While temperatures could touch 90° in the Nation’s Capital this afternoon, the 90s will certainly return tomorrow.  Whether the 90s return today or tomorrow, it will start the next heat wave for Washingtonians.  A “heat wave” is three or more consecutive days of high temperatures that meet or exceed 90°.  There have been 45 days of 90° heat so far in 2019.  That’s already greater than the annual average of 36.  Last year finished with 42 days of 90° heat.  DC’s highest annual total of 90° heat is 67 days that occurred twice: once in 1980 and, more recently, in 2010.

That’s not to say Washingtonians will challenge that record – but approaching 60 days of 90° heat is a possibility.  DC residents should reach 50 such days by the middle of next week.  A significant number of DC’s 90° days this summer occurred in July (22).  What’s made 2019 unusual is while DC has already had more 90° days than average for an entire year, no triple-digit temperatures have occurred.  The hottest temperature so far this year was 99° on July 21.  

Although average high/low temperatures decrease in August and September, 90° temperatures are common in both months.  DC’s last 90° temperature of 2018 didn’t occur until October 4, while the latest 90°/+ on record was on October 11, 1919.  Washingtonians could see 90° heat well into the fall season.  NOAA’s Climate Prediction Center expects above average temperatures to dominate local weather headlines in the DC Metro Area for much of the next six weeks through the end of September.  That said, it will be interesting to see how many 90° days the Nation’s Capital finishes with in 2019.