Sunrise on the Lincoln Memorial. (Angela N. via Flickr)

Cloudless Sundays should be cause for celebration in late September. But not when they are accompanied by 90-degree heat and high humidity. You can be forgiven if you spent most of today inside and near an air conditioner.

Listen to the latest forecast:

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Through Tonight: Mostly clear, warm and muggy again. Overnight temperatures will be similar to last night's, ranging from the low to mid-60s in the suburbs and right about 70 downtown. Light and variable wind.

View the current weather conditions at The Washington Post.

Tomorrow (Monday): Some early morning patchy fog will quickly burn off. Mostly sunny with another day of warm and humid conditions. Highs will reach the upper 80s, with dew points in the mid- to upper 60s. Some high clouds may work their way in tomorrow night. Otherwise, warm and muggy conditions prevail, with overnight lows in the 60s.

See Brian Jackson's  forecast into early 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 Dr. Gridlock.

Record warmth abounds: It's quite warm across much of the northern part of the country today. So warm, in fact, that many daily maximum temperature records have been broken. So perhaps we can take solace in that many of our fellow citizens are sweating through this Sunday just like we are.

Many temperature records fell on Sunday afternoon.

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