The temperature touched at least 90 degrees in D.C. early this afternoon (as measured at Reagan National Airport) for the 25th time this calendar year. That means, with almost half of the summer still to come, we have already surpassed last year’s total number of days at or above 90 degrees.
The 25 90+ days is about 8 more than average year to date and ties for the 20th most on record.
But 2015’s 90+ count is not even close to that of the years with the most at this time of year. In D.C. weather records, which date back to 1872, the years with the most 90+ days through July 21 are 1994 with 39 such days, 2010 and 1991 with 38, and 1872 with 36.
It’s also worth noting that of this year’s many 90+ days, most barely reached the threshold. D.C. has had many days with highs of just 90, 91, or 92.
Through this past Saturday, only two days had hit at least 95 – which was slightly below average. The highs of 98 and 97 Sunday and Monday added two 95+ days to the 2015 count – bringing the total number (of 4 such days) to almost exactly average for the time of year.
In other words, for much of the summer of 2015, the heat in Washington, D.C. has been persistent, though not particularly extreme.
Monday morning’s historically warm low temperature
While most of D.C.’s hot temperatures this summer have not been record-challenging, the past two oppressively muggy mornings have proven exceptional.
On Monday morning, the low in D.C. fell to a mere 82 degrees, the warmest on record for July 20 and tied for the third warmest of any low temperature back to 1871.
As Capital Weather Gang’s Ian Livingston pointed out Monday afternoon, D.C. has logged a stunning 21 days with lows at or above 80 degrees over the last 5.5 summers (since 2010) – an average of about 4 per year, compared to 31 such days over 137 summers between 1872 and 2009 – an average of about one every four years.
(Dulles Airport also set a record high minimum temperature for the date Monday morning, only falling to 75 degrees).
This morning. D.C.’s low was only 84 degrees, which would match the warmest low temperature ever recorded in Washington (July 23 and 24, 2011 and July 16, 1983). However, the temperature is likely to drop to around 79 or 80 by midnight thanks to a cold front passing through this evening – so will likely end up short of the mark.