D.C. area forecast: Summer’s most uncomfortably hot week begins

Today’s Daily Digit

A somewhat subjective rating of the days weather, on a scale of 1 to 10.

4
Just the start of a long, hot, humid week. Gets worse before it gets better.

Express Forecast

Today: Mostly sunny, hot and humid. Highs 90-95.

Tonight: Partly cloudy. Lows 70-75.

Tomorrow: Mostly sunny, hot and humid. Highs 93-97.

FORECAST IN DETAIL

Temperature Map

Temperatures: Latest D.C. area temperature map. See interactive map on our Weather Wall.

Despite this summer’s relentless humidity, we’ve managed to hold back the heat, with not a single day reaching the 95-degree threshold.  As a large heat dome overtakes and overwhelms the region this week, we break through the resistance at 95, and may push 100. Heat indices could surpass 105 a few afternoons. That means, for the first time this summer, the National Weather Service will likely hoist heat advisories, and we may see some air quality alerts issued as well.

Today (Monday): After patchy morning fog, the sun breaks out and we start baking. Highs reach the low-to-mid 90s with maximum heat indices near 100. A light wind from the northwest at 5-10 mph offers little relief. Confidence: Medium-High

Tonight: Not the worst evening ever, if you don’t mind the mugginess.  Under partly cloudy skies, temperatures slowly fall back through the 80s, with lows 70-75 (warmest downtown). Light winds. Confidence: High

For related traffic news, check out Dr. Gridlock. Keep reading for the forecast through the weekend…

Tomorrow (Tuesday): It’s just like Monday, but we add a couple degrees to high temps.  Many of us experience highs in the mid-90s, with the humidity levels bumping heat indices as high as 102-105. There’s little wind to ease the heat. Confidence: High

Tomorrow night: On the sultry side. Temperatures take their sweet time falling back through the 80s, with overnight lows in the upper 70s in the city, with some low 70s in the cooler suburbs. Confidence: High

A LOOK AHEAD

Wednesday through Friday is a broken record forecast (but it remains to be seen whether we break any records for heat).  Highs each day are in the mid-to-upper 90s. And we can’t rule out some isolated triple digit heat. Factoring in the humidity, heat indices may get as high as 105-110.  High pressure overhead probably squashes any storms that try to form, with generally partly to mostly sunny, but hazy skies.  With the air so stagnant, some air quality alerts may be required.  Overnight lows range from the low 70s to as warm as near 80 downtown.  Confidence: Medium-High

The weekend begins a transition away from the scorching heat.  Saturday’s still on the toasty side with highs into the 90s, but a cold front may try to set off some late day or overnight storms (some of which could be strong).  Saturday night’s lows should generally be in the 70s (although some 60s are possible if the front penetrates far enough south). The front may stall out over the region Sunday, keeping us humid with a chance of storms. Or, it may push far enough south for us to dry out and cool off a bit. I’ll go with a compromise solution for Sunday for now, with highs 85-90 and a 40 percent chance of showers/storms. Confidence: Low-Medium

Jason is currently the Washington Post’s weather editor. A native Washingtonian, Jason has been a weather enthusiast since age 10.
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