Temperatures in the 90s with high humidity could make it feel like almost 100 degrees Friday, and also fuel possible severe thunderstorms in the afternoon or evening.
Highs are forecast in the lower 90s. With dew points around 70 degrees indicating uncomfortable levels of humidity, the heat index is forecast to reach the upper 90s.
The heat index at Baltimore/Washington International Thurgood Marshall Airport peaked at 95 on Thursday and 97 on Wednesday, according to the National Weather Service.
As of 1 p.m., it was 89 degrees at BWI and, factoring in humidity, felt like 94 degrees.
If skies remain mostly clear for much of Friday, the sunshine could create instability in the atmosphere that could trigger afternoon or evening storms. The storms would be expected to carry risks of severe wind gusts and lightning.
Storm threats Friday stretch from the southern Plains states across the Ohio and Tennessee valleys into the mid-Atlantic, according to the weather service's Storm Prediction Center.
More heat but slightly lower humidity is forecast Saturday, with highs again in the lower 90s. Temperatures are expected to peak in the upper 80s on Sunday, with mostly sunny skies throughout the weekend.