We have by now reached the time of year when 90 degree days may not be normal but are no surprise. Washington’s official temperature Friday was 93 degrees, the year’s highest, far above average, but scarcely startling.

Certainly, Friday’s 93 produced perspiration, created discomfort and simulated summer. However, Washingtonians have seen its like before. And may again.

Washington’s all-time high for May 19 is 96 degrees. That was recorded 20 years ago at Reagan National Airport, and also in 1911 before National Airport existed.

This week gave all three of the region’s major airports their hottest days of 2017.

At Dulles International Airport, the top temperature thus far was Wednesday’s 92. Subsequent highs there of 90 on Thursday and 90 on Friday permitted residents of the Dulles area to take pride in enduring a heat wave, which often is defined as three successive 90 degree days.