* Flash Flood Watch 3 p.m. Monday to 6 a.m. Tuesday *

8:45 p.m. - Lingering showers and storm possible overnight while heavy rain threat Monday is a concern

The storm described in the previous updates in Loudoun and Montgomery County has collapsed entirely and we no longer need to worry about it.

There may be some additional showers and storms overnight (some heavy storms are currently tracking through northern Maryland), which could be locally heavy, but the more significant and widespread heavy rain threat may develop Monday afternoon and evening. Scroll down for our outlook for tomorrow.

Unless significant severe weather develops in the immediate area, this will be our last update tonight.

8:25 p.m. - Storms weakening in the immediate area

The strong to severe storm that tracked through central Loudoun and southern Montgomery counties has weakened quickly in the last 20 minutes, dissipating to mostly showers along the northern branch of the Beltway.

But they were pretty vigorous to the west. Leesburg clocked a gust to 59 mph, and Dulles 45 mph. Some reports of downed trees have come in from Loudoun County. Readers reported very strong winds and torrential rain around Potomac, Md. in Montgomery County as well:

Another area of heavy thunderstorms hit Frederick (where it’s still raining) bringing down numerous trees and powerlines in the area. Radar indicated over an inch of rain fell and winds gusted to 52 mph.

7:50 p.m. - Strong to severe storms from Leesburg to Silver Spring

All of the heat and humidity from earlier today is fueling some big storms tracking through Washington northern suburbs. Radar shows heavy storms from Leesburg to Silver Spring. These storms are generally headed east-southeast, but slowly, and will produce very heavy rain, lightning, and pockets of strong to damaging winds.

Severe thunderstorm warnings are in effect all along this line of storms from northern Fairfax County to southern Montgomery County, including northwest Washington, until 8:15 p.m.

Original post from late afternoon

It was the hottest day of the summer as Washington hit 99, while Dulles and Baltimore both made it to the century mark. Dulles hit 100 for the first time since 2016 and was a just a degree shy of its record of 101, set in 1991. These temperatures, combined with the humidity, produced heat indexes in the 105- to 115-degree range.

A few storms are possible this evening and overnight before much more widespread storms develop as Monday wears on, signaling the beginning of the end of this brutal stretch of heat and humidity.

The National Weather Service has issued a flash flood watch for Monday afternoon and night, predicting “multiple rounds of showers and thunderstorms” with one to 1.5 inches of rain and isolated amounts up to four inches.

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Through tonight: A few showers and thunderstorms may develop sometime after 5 p.m., with the main hazard being heavy rain and gusty winds. While the best chance for a storm is this evening, we could also see some widely scattered activity through the night. It remains very warm and humid overnight. Low temperatures only fall to 75 to 80 degrees, and it feels even more sultry, with heat index values only dipping to 85 to 90 downtown (dew points hover in the 70s).

View the current weather at The Washington Post.

Tomorrow (Monday): With mostly cloudy skies, it will be hot, but not nearly as hot as this weekend. Highs in the low 90s with dew points in the low to mid-70s will create max heat index values near 100 degrees. Widespread showers and thunderstorms develop during the afternoon, with several periods of heavy rain heightening the chances for localized flash flooding. Scattered showers and storms continue tomorrow night with lows in the low 70s.

See Rick Grow’s forecast through the week. And if you haven’t already, join us on Facebook and follow us on Twitter and Instagram. For traffic news, check out Gridlock.

France set to bake: Just a few weeks ago, France set an all-time hottest temperature of 46 Celsius (114.8 Fahrenheit). But will that record even last a month? Take a look at the forecast maximum temperatures for the upcoming week:

Paris has a reasonable chance to break its record high temperature of 40.7 Celsius (104.7 degrees), set in July of 1947.

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