Steps adjacent to the Lincoln Memorial on Aug. 7, 2016. ( Paul Scott via Flickr )

This story has been updated.

For more than a month, D.C.’s temperature failed to dip into the 60s even once. This made for the longest such period in 145 years of record-keeping.

Officially, the mercury remained at 70 degrees or higher for 35 straight days, three days more than the prior longest streak, ending Aug.15, 1980.


The streak finally ended early Tuesday morning when the temperature dipped to 68 degrees. Had it remained two degree warmer, the streak threatened to last another seven to 10 days, at least – given very warm and humid weather in the forecast.

Embedded within the 35-day streak of temperatures not lower than 70 degrees was a five day streak of temperatures not lower than 80 degrees, the second longest on record.

The lack of cooling has practical implications for quality of life.

When the temperature stays this high around the clock, it places more demands on our cooling systems and energy consumption rises.

Our lakes and rivers stay warm, which can lead to harmful algal blooms.

For the homeless and people without air conditioning, the cumulative stress from the lack of cooling can increase the likelihood of heat-related illness.

This stretch of warm round-the-clock temperatures applied only to the D.C. urban core — as reflected by the temperature measured at Reagan National Airport (where official measurements are taken).

While Reagan National Airport didn’t fall below 70 for 35 days, Dulles International Airport — farther away from the city — did so on 13 days in the same span, including five of the first eight days of August.