A dry heat pressed into the D.C. area today, with highs topping out in the mid-90s. Humid air floods into the region overnight and the heat takes a step up tomorrow. The end result is a miserably hot and humid Friday, with record high temperatures possible.
Through Tonight: Tolerable humidity levels this evening are gradually washed out overnight as the air mass moistens. The thickening air doesn’t allow temperatures to fall very much with lows in the mid-to-upper 60s in the cooler suburbs to the mid-to-upper 70s downtown. There’s a light breeze from the southwest at 5 to 10 mph under partly cloud skies. I can’t rule out a late night (after midnight) or pre-dawn thunderstorm (20 percent chance) - with best odds north of town. (Link to radar)
Friday: Blistering heat and moderate to high humidity under partly to mostly sunny skies. Morning temperatures quickly ramp up through the 80s with 90s by late morning. Mid-to-late afternoon temperatures near the century mark with a 50/50 chance of exceeding it. See record information below. Heat indices top out near 105. Any isolated thunderstorm activity probably holds up overnight but could start to fire in the higher terrain to the northwest by evening.
Friday’s records: Record highs are 101 at Reagan National, DCA, (attainable), 105 at BWI (out of reach), and 95 at Dulles (IAD, attainable). DCA’s all-time June record of 102 is a stretch, but has a 15% chance of being matched and 10% chance of being exceeded. I think tonight’s low temperatures will be low enough not to threaten the record high minima of 81, 76, and 74 at DCA, BWI, and IAD, respectively.