WASHINGTON, D.C. — A cold, clear night left many suburbs north and west of Washington waking up to temperatures in the 30s on Monday morning. Freeze warnings and frost advisories covered parts of Virginia and the surrounding area from Sunday night into Monday morning. The good news is that a sunny and milder stretch takes over the rest of the week, with highs mostly in the 60s.
Why It Got So Cold Overnight
Our forecast team pointed to two key ingredients: clear skies and calm winds. When there are no clouds overhead, the warmth from the ground escapes quickly into the sky after sunset. Calm winds let the coldest air settle near the ground, especially in valleys and rural areas.
That is why the suburbs turned much colder than the city. Washington itself stayed in the low 40s, while many outlying areas dropped into the 30s.
What Freeze Warnings and Frost Advisories Mean
These two alerts sound similar, but there is an important difference. A frost advisory means temperatures are cold enough for a thin layer of ice crystals to form on grass, cars and plants. A freeze warning is more serious, meaning temperatures are expected to drop low enough to damage or kill sensitive plants and unprotected outdoor plumbing.
Both alerts were issued on Sunday afternoon and ran through Monday morning. Gardeners were urged to cover or bring in sensitive plants before going to bed.
Where the Freeze Warnings Were
The freeze warning area, the colder of the two zones, covered a wide band west and north of the city:
- Hagerstown sat inside the freeze warning area, one of the colder spots in the region overnight.
- Westminster was also in the freeze zone as cold air settled north of
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- Warrenton fell inside the freeze warning area along the Interstate 66 corridor.
- Orange in Virginia was included in the freeze warning as well, at the southern end of the zone.
Where the Frost Advisories Were
The frost advisory areas sat closer to the city and on the edges of the freeze zone. Leesburg was inside the frost advisory area, where frost formed on lawns and windshields early Monday. Frost advisories also stretched near Bel Air and into parts of the Shenandoah Valley near Luray and Harrisonburg…