The Washington PostDemocracy Dies in Darkness

After third straight 90-degree day, Washington notches first heat wave of 2018

Dixie Canales holds her one year old daughter Camilla, in the cool zone misting spray at Nationals Park as the Washington Nationals take on the Pittsburgh Pirates. (Jonathan Newton/The Washington Post)
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This story, first published at 12:37 p.m. Wednesday, was last updated at 4:45 p.m. on Friday.

For a third day in a row, Washington’s temperature soared to at least 90 degrees, officially meeting the criterion of a heat wave, this year’s first.

It marked the earliest heat wave in Washington since 2002, according to Capital Weather Gang’s Ian Livingston.

The three straight 90-degree days matched Washington’s longest such streak on record in the first 10 days of May, a remarkable contrast from the chilly weather in the 50s just several days prior and throughout April.

Friday’s temperatures hit at least 90 at all three airports in the region. Some 20 degrees above normal levels around 70, they neared records:

  • Reagan National Airport, Washington’s official weather station, hit 90, a little short of the record of 93 from 1928.
  • Baltimore-Washington International Marshall Airport hit 90, tying the record from 2001.
  • Dulles International Airport hit 90, tying the record from 2001.

Thursday also featured record-challenging heat:

  • National hit 90 degrees, just one degree shy of the record of 91 set in 1965.
  • BWI hit 92 degrees, breaking the record of 91 from 1913.
  • Dulles hit 90, just off the record of 92 from 1965.

The day before, all three airports set record highs for the date.

  • National exceeded 90 degrees for the first time this year on its way to 91, breaking the daily record of 89 from 1930.
  • BWI hit 90, breaking the record of 88 from 1951.
  • Dulles hit 88 degrees, tying the record set in 2010.

The 90-degree weather in Washington arrived about two weeks ahead of schedule. On average, Washington does not post its first 90-degree day until May 18. That said, there is a lot of variability in when Washington notches its first 90, and it has happened earlier in a number of other years.

Last year, for example, Washington first reached 90 on April 29, based on measurements at National Airport. The earliest it has ever hit 90 was March 22, 1907, when measurements were taken at 24th and M streets in the District. The latest first 90-degree day ever recorded was July 12, 1979.

While Washington experienced heat more characteristic of July, humidity levels mostly remained in check.

Dew points, the best measure of how humid it is, were only in the 40s on Wednesday — which is very dry. Thursday’s and Friday’s dew points in the 50s into low 60s offered a hint of mugginess, but were still  low compared with levels in the 60s to near 70 that are common in midsummer.

As a cold front moves into the region Friday night and over the weekend, temperatures are forecast to retreat into the 70s and 60s Saturday and Sunday, with on-and-off rain.