* Frost advisory for western Loudoun, northern Fauquier and Frederick (Md.) counties 2 a.m. to 9 a.m. Monday *

It was quite the chilly start for this last Sunday of the summer. Downtown D.C. officially dropped to 46 degrees, the coolest reading since May. Many other locations were even colder, with lots of frost showing up on grassy surfaces and car windshields. Ample sunshine helped things warm back up this afternoon, but we are in for another chilly night as a sprawling high-pressure system continues to keep things tranquil over the entire Eastern United States.

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Through tonight: Staying mild through the rest of the daylight hours, but temperatures will fall off rather quickly once the sun sets. Winds will become nearly nonexistent as well, so I am expecting low temperatures to be a few degrees colder than last night’s. D.C. and areas inside the Beltway will bottom out in the low to mid-40s again. But some of the northern and western suburbs will drop into the upper 30s, with frost possible. A frost advisory is in effect for our far western areas where lows could even settle in the mid-30s.

View the current weather at The Washington Post.

Tomorrow (Monday): A chilly start for early risers on the last official day of summer. No weather issues to speak of again, with clear skies, ample sunshine and mild temperatures. Highs will be similar to today’s, topping out in the mid- to upper 60s. Clear, calm and cold in the evening, with temperatures ranging from the upper 30s to low 40s.

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