It was D.C.'s most humid July in over 90 years. What will August bring?

Washington Post

4 days ago

July was super-steamy, the most humid D.C. has experienced since 1933.
A refreshingly cool start to August might put some spring in our steps, but the month will soon find its way back to its typical sticky self.
We project near to above average temperatures during August, or 0 and 2 degrees above the norm of 79.4 degrees. We're expecting below average rainfall, or 0.5 to 1.5 inches below the norm.
We have more confidence in the temperature forecast as the summer precipitation is notoriously difficult to predict because of the hit or miss nature of thunderstorms.
Below, we present model forecasts for temperature and precipitation for the first half of August. The first week features below normal temperatures while they rebound by the second week.
Rainfall is predicted to be slightly above normal both weeks. However, in recent weeks, models have overpredicted precipitation at times, so we are taking that into account in our forecast.
Models predict a drier second half of the month, with above normal temperatures, as shown in the images below:
Weather patterns during August often mimic July — another reason we lean toward a warmer-than-normal month.
July was 1.4 degrees hotter than normal and the 10th hottest on record. As noted, it was the second most humid July on record — with an average dew point of 71 degrees. (Dew points over 70 signify very high humidity.)
Only July 1933 was more humid — with an average dew point of 75. However, we are skeptical of that data point as 75 seems unrealistically high and weather measurements weren't as consistent and reliable in the 1930s compared to today.
Including June, this has been the most humid summer on record in D.C. so far.
July rainfall was 0.79 inches below normal and the driest since 2016 in D.C., based on measurements at Reagan National Airport. However, many surrounding areas in the region saw above normal rainfall.
Our July outlook correctly predicted the above normal temperatures. Our rainfall prediction was too high for D.C. but accurate for many nearby locations.
The month's highest temperature was 98 degrees on July 25, a shade lower than the June's high of 99. But the relentlessly high humidity more than made up the difference.
The high humidity elevated nighttime temperatures. Lows dipped below 70 degrees only once. The month's lowest temperature of 69 is tied with July 2023 for the second warmest minimum July temperature on record (only 2020′s lowest July temperature of 71 was warmer).
At the three official measurement locations in the area (in D.C., Dulles and Baltimore), only one record was set. On July 14, Baltimore received 1.95 inches of rain, a record for the date.
Year-to-date, this year ranks as the 8th warmest on record, but not as warm as last year.
Precipitation is a slightly above normal year-to-date, and slightly wetter than last year.
Jason Samenow contributed to this report.