Excessive Heat Watch Thurs. p.m. | Code orange air quality today: unhealthy for sensitive groups | CWG’s Heat wave, hot weather guide

Today’s Daily Digit
 
A somewhat subjective rating of the
day’s weather, on a scale of 0 to 10.

 
About as hot & humid as yesterday - not so nice, but a notch below dangerous Thurs-Sat heat.
 
Get the ‘Digit’ on Twitter
EXPRESS FORECAST

Today: Partly to mostly sunny & humid. 20% chance of p.m. storm. Mid-90s. | Tonight: Warm & muggy. 20% chance of evening storm. Mid-70s to near 80. | Tomorrow: Mostly sunny, dangerously hot & humid. Upper 90s to near 100. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

It’s another very hot and humid one today. But for Thursday, Friday and Saturday, we’re talking downright dangerous heat and humidity with highs in the upper 90s to low 100s and maximum heat indices near 110-115. If you can avoid being outside more than a few minutes at a time during the late mornings through late afternoons, do it. And make sure you don’t end up on a Metro car with no A/C. The heat may or may not subside ever-so-slightly on Sunday, with real relief probably waiting for the next work week.

Today (Wednesday): Both the heat and humidity are similar to yesterday - bad, but not as brutal as what’s to come. Beneath partly to mostly sunny skies, highs reach the mid-90s most spots (low 90s close to the Chesapeake Bay) with afternoon heat indices maxing out in the upper near 100-105. An isolated storm is possible during the afternoon into evening, but chances for any given location are only around 20%. Confidence: Medium-High

Tonight: Unless knocked down more quickly by an isolated storm (20% chance), evening temperatures only slowly fall back through the 90s into the 80s. The muggy air remains locked in place under partly cloudy skies, with overnight lows only down to near 80 downtown and the mid-70s in the suburbs. Confidence: Medium-High

Keep reading for the forecast into next week...

Tomorrow (Thursday): The truly wicked heat and humidity arrive as mostly sunny skies help push highs to the upper 90s to near 100 (records to beat:104 at National, 101 at Dulles, 104 at BWI) and afternoon heat indices to near 110. Winds from the southwest are too light to offer much of any relief. Afternoon/evening thunderstorm chances are less than 20%. Confidence: High

Tomorrow night: Mostly clear, still super muggy, and slightly warmer than tonight. Lows probably only make the low 80s downtown, with mid-to-upper 70s in the burbs. Confidence: High

A LOOK AHEAD

Friday and Saturday are just awful. Highs climb to the upper 90s to low 100s under mostly sunny skies, and with high humidity the afternoon heat index could reach near 110-115. Any storms are probably isolated with overall chances around 20% each day. Friday and Saturday night lows are disturbingly high - in the upper 70s to low 80s (suburbs) to low-to-mid 80s (downtown). Friday records to beat:103 at National, 98 at Dulles, and 101 at BWI. Saturday records: 101 at National, 99 at Dulles, and 102 at BWI Confidence: High

Models have wavered as to whether the upper-level high pressure system responsible for the extreme heat may break down a bit by Sunday, allowing for more clouds and an increased chance of showers/storms, and taking the edge off the heat. As of now, I’m not seeing a big difference in the overall pattern, so unfortunately my Sunday forecast is for partly to mostly sunny skies, highs in the mid-90s to near 100, high humidity, and a continued chance of an isolated storm. Confidence: Medium

A cold front does appear set to put an end to the triple-digit threat come Monday and Tuesday, with highs in the 90s Monday and maybe only near 90 Tuesday. The front means an increase in clouds and storm chances, followed by decreasing humidity once it passes through sometime in the Monday-Tuesday timeframe. Confidence:Low-Medium