Dangerous Heat Wave from the Midwest to East Coast; Severe Thunderstorms Across Portions of the Upper Midwest

A dangerous heat wave will persist through this weekend. Widespread warnings and advisories for the heat cover most of the eastern two-thirds of the U.S. Heat indices will surge past 100 degrees and even rise above 110 in many locations. Northwest of this dome of heat, severe thunderstorms with the possibility of strong tornadoes and widespread significant wind damage are possible into tonight. Read More >

Hazardous Weather Conditions

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Current conditions at

Gaithersburg - Montgomery County Airport (KGAI)

Lat: 39.17°NLon: 77.17°WElev: 495ft.

A Few Clouds

33°C

92°F

Humidity	56%
Wind Speed	W 11 km/h
Barometer	1013.7 mb (29.92 in)
Dewpoint	23°C (74°F)
Visibility	16 km
Heat Index	39°C (102°F)
Last update	19 Jul 6:56 pm EDT

More Information:

Local Forecast Office More Local Wx 3 Day History Mobile Weather Hourly Weather Forecast

Extended Forecast for

Derwood MD

Excessive Heat Watch July 21, 11:00am until July 21, 09:00pm

Excessive Heat Warning July 20, 11:00am until July 20, 09:00pm

Excessive Heat Warning until July 19, 09:00pm

Click here for hazard details and duration

Excessive Heat Watch

Excessive Heat Warning

...

Excessive Heat Warning until July 19, 09:00pm

NOW until
9:00pm Fri

Excessive Heat Warning
Tonight

Partly Cloudy
Low: 26 °C
Saturday

Hot
High: 37 °C
Saturday
Night

Partly Cloudy
Low: 26 °C
Sunday

Mostly Sunny
then Chance
T-storms
High: 37 °C
Sunday
Night

Chance
T-storms
Low: 24 °C
Monday

T-storms
Likely
High: 32 °C
Monday
Night

Showers
Likely
Low: 20 °C
Tuesday

Chance
Showers
High: 27 °C

Detailed Forecast

Tonight

Partly cloudy, with a low around 26. West wind 5 to 10 km/h.

Saturday

Mostly sunny and hot, with a high near 37. Heat index values as high as 44. West wind 8 to 11 km/h.

Saturday Night

Partly cloudy, with a low around 26. West wind 3 to 8 km/h.

Sunday

A chance of showers and thunderstorms after 2pm. Mostly sunny and hot, with a high near 37. Heat index values as high as 43. West wind 8 to 11 km/h. Chance of precipitation is 30%.

Sunday Night

A chance of showers and thunderstorms, mainly before 2am. Mostly cloudy, with a low around 24. West wind 5 to 8 km/h. Chance of precipitation is 40%.

Monday

Showers and thunderstorms likely, mainly after 8am. Mostly cloudy, with a high near 32. Chance of precipitation is 70%.

Monday Night

Showers likely and possibly a thunderstorm. Cloudy, with a low around 20. Chance of precipitation is 70%.

Tuesday

A chance of showers. Mostly cloudy, with a high near 27. Chance of precipitation is 50%.

Tuesday Night

Partly cloudy, with a low around 17.

Wednesday

Mostly sunny, with a high near 28.