D.C. summer outlook: It may not be insanely hot for a change.

But still expect plenty of D.C.’s trademark mugginess.

After a week of some summerlike weather with several days topping 90 degrees, Memorial Day weekend slammed the brakes on our premature descent into mid-July. That was just a temporary setback, though. In D.C., summer always wins.

Here is our annual summer outlook.

In our view, this summer has a slightly better than 50-50 chance to be the first summer with below-normal temperatures since 2009. But this partly reflects the fact that the baseline for what we consider “normal” has gotten warmer.

This outlook is relative to the new 30-year climate normals that were released last month, based on average weather between 1991 and 2020. Between the previous baseline period (1981 to 2010) and the latest (1991 to 2020), June, July and August each warmed at least one degree, while the summer overall heated up 1.2 degrees.

Whereas each of the past 10 summers was warmer than normal using the old baseline (77.7 degrees), three of them would be cooler than normal using the new baseline (78.9 degrees). Our forecast for this summer’s average temperature is close to the old baseline and a little cooler than the new one.

In other words, we’re not forecasting this summer to be either exceptionally hot or memorably refreshing. Rather, we expect this summer to be hot and humid, like D.C. summers tend to be. But it should come as a welcome departure from numerous recent summers; seven of D.C.’s eight hottest summers on record have occurred since 2010, including last year.

https://www.washingtonpost.com/weather/2021/06/01/dc-summer-outlook-2021/?