 And then we begin our ramp upward again temperature-wise, Saturday above 90 degrees. By Sunday, Monday, and Tuesday, upper 90s to even close to 100 degrees across the area. It's 90 at Dulles and BWI Marshall and Reagan National. Heat index value downtown at 104 degrees. Oof! The hot forecast is brought to you by Lenn the Plumber Heating and Air. Trusted same-day service, seven days a week.