D.C. area forecast: Heat and humidity then tropical moisture invade, but eventual relief July 4

Today’s Daily Digit

A somewhat subjective rating of the day’s weather, on a scale of 1 to 10.

4
Here we go: uncomfortable humidity on the rise again.

Express Forecast

Today: Mix of sun/clouds. Highs: 89-94.

Tonight: Isolated evening storm; partly cloudy, muggy. Lows: 70-76.

Tomorrow: PM showers/storms.  Highs: 90-95.

FORECAST IN DETAIL

Temperature Map

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

Today we launch into a three-day burst of moderately high heat and humidity.  The escalating mugginess is complemented by rising shower and storm chances tomorrow and Thursday (maybe lingering into early Friday).  The tropical system off the Southeast coast could enhance Thursday’s rain, but it seems like we shift back to a lower humidity air mass later on Independence Day (in time for fireworks) and aim for another nice weekend.

The interesting aspect of this summer so far is that whenever we get into the thick of the classic D.C. heat and humidity, it tends to persist for only a few days with relief not far behind it.  This climatic conveyor belt of variability is quite different from the stalled hot patterns of the 2010-2012 summers and closer to last year with its variability (but so far, a bit hotter).

Today (Tuesday): July gets off to a muggy start thanks to a sticky air flow from the south at 5 to 10 mph.  Sky conditions vary, but should be on the partly sunny side as afternoon temperatures reach to around 90F for most. Some typically hotter spots could see lower to middle 90s.  With afternoon dew points in the middle to upper 60s, the heat index levels should be up into the uncomfortable middle to upper 90s.   Confidence: Medium-High

Tonight: We can’t rule out an evening storm (20 percent chance); Otherwise, it’s partly cloudy and very muggy with lows only in the lower to middle 70s as (not-strong-enough) breezes come from the south and southwest at 5 to 10 mph.  Unless rain materializes (unlikely), this is probably the least comfortable overnight of the week.  Confidence: Medium-High

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

Tomorrow (Wednesday): The day starts partly to mostly sunny with soaring temperatures through the 80s. Before showers/storms flare up in the afternoon, highs should manage to reach the low to middle 90s. Humidity remains robustly uncomfortable.  Heat indices range from the upper 90s to low 100s around the time of peak temperatures (midday into the afternoon).  Winds from the south and southwest at 5 to 10 mph.  Precipitation may add up to about a half inch in many locales, with some higher totals are possible in heavier storms.  Confidence: Medium

Tomorrow night: Scattered showers and storms during the evening hours with just a slight chance of a widely scattered storm overnight.  Partly to mostly cloudy skies with lows in the low to middle 70s keep conditions quite muggy.  Additional precipitation totals could be anywhere from a trace to a tenth of an inch, locally higher around any slower thunderstorms.  Confidence: Medium

A LOOK AHEAD

Thursday brings another round of widespread showers and storms by afternoon, some of which could deliver very heavy rains as we watch a possible tropical infusion of moisture.  Partly to mostly cloudy skies in the morning shift to mostly cloudy in the afternoon.  Increased cloud cover and rain risks should hold highs down into the upper 80s to near 90F, but no relief from the humidity.  Showers and thunderstorm risks carry into the evening with a chance of overnight activity too as lows drop to near 70F under partly to mostly cloudy skies.  Confidence: Medium

Fourth of July Friday has a real opportunity to clear out by afternoon following some morning clouds and scattered shower/storm risks (best chances east of the District).  Highs are aiming for the lower to middle 80s yet with dew points dropping to the more comfortable lower 60s by afternoon.  Friday night fireworks still look like they could be a winner with just a few clouds around, but much more comfortable temperatures.  Confidence: Medium

The weekend should continue the theme of more comfortable conditions thanks to lower humidity and temperatures only in the 80s during the afternoons along with mostly sunny skies.  Overnight lows dip into the 60s to near 70 under mostly clear skies and still low humidity. Confidence: Medium

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