A man wears an umbrella hat for shade during Saturday's swelter near the Washington Monument. (Alex Wroblewski/Getty Images)

* Excessive heat warning through 9 p.m. today and excessive heat watch from 11 a.m. to 9 p.m. Sunday*

**10:20 pm Update: The small storm in D.C. weakened without ruining celebrations on the Mall, and only a slight threat of showers and thunderstorms remains throughout the rest of this stifling night.**

9:35 pm Update: A lone thunderstorm triggered a severe thunderstorm warning for D.C. and adjacent portions of Montgomery and Arlington Counties. The storm moved into D.C. during commemorations for the 50th anniversary of the Apollo 11 Moon landing taking place on the National Mall.**

Highs in the upper 90s (at least 97 at all three major airports in the region) made today the hottest of the year so far and, adding in the suffocating humidity, it felt like 105 to 115 degrees.

A juiced-up atmosphere and remnants of Friday night’s strong storms over the upper Midwest could kick off some isolated storms this evening, before one more final day of unbearable heat and humidity on Sunday.

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Through tonight: Isolated severe thunderstorms are a possibility from 6 to 10 p.m., especially around and east of the Interstate 95 corridor. Otherwise, it stays very hot and uncomfortably humid overnight. Heat index values will hover in the 90s deep into the night, with low temperatures ranging from 80 to 83 degrees combined with dew points in the mid-70s. In fact, the heat index may not drop below 90 degrees in urban areas around the District.

View the current weather at The Washington Post.


Life-size projections of the Saturn V Apollo moon rocket appear on the Washington Monument. (Tim Brown via Flickr)

Tomorrow (Sunday): Back at it again tomorrow with temperatures off to the races once the sun rises. The heat index will be dangerously high once again (105 to 110 degrees or more) as high temperatures ranging from 95 to 100 degrees combine with dew points in the mid- to upper 70s. Late-afternoon clouds and strengthening west wind may mix out the humidity just a bit but probably not enough to make a tangible difference. Scattered showers and thunderstorms develop in the evening and overnight hours tomorrow, with temperatures and dew-point values in the mid- to upper 70s.

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

Wait for Wednesday: I’ll just go ahead and leave this right here. Have a look at your forecast for Wednesday:

Wednesday, July 24: Mostly sunny with a high temperature around 83 degrees and comfortable dew point values in the mid- to upper 50s. Winds will be light (and quite refreshing) out of the northwest.

Hang in there, people. And do make sure you are staying as cool and as hydrated as you can be.

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