Freeze warnings and frost advisories issued for Washington area

WEATHER NEWS: Freeze warnings and frost advisories issued for Washington area


With the coldest air of fall so far, chances are good that parts of the area will see their first freeze of the season during at least one of the next two nights. Areas that don’t quite reach freezing will nevertheless probably see frost.

Frost advisories are in effect for the District and immediate surrounding counties from 2 a.m. to 9 a.m. Wednesday.

“Temperatures around 33 to 36 degrees will result in frost formation,” the National Weather Service in Sterling, Va., wrote. “Frost could kill sensitive outdoor vegetation if left uncovered.”

Freeze warnings have been hoisted for areas north, west and south of the frost advisories, including Frederick in Maryland and western Loudoun, Prince William and Fauquier counties in Virginia. These warnings are issued when temperatures are expected to fall to or below 32 degrees and the end of the growing season is anticipated.

“Frost and freeze conditions will kill crops, other sensitive vegetation and possibly damage unprotected outdoor plumbing,” the Weather Service wrote in its warning statement.

Winter chill engulfs eastern U.S. as summer warmth swells in West

Low temperatures Wednesday morning are forecast to dip to the low and mid-30s in most spots, but closer to 40 in downtown Washington.

The cold, sourced from the Arctic, is also supporting the first accumulating snow in the mountains of West Virginia, western Maryland and southwest Pennsylvania.

Mid-Atlantic mountains to see first accumulating snow of season

Expect more frost and freeze alerts on Thursday morning when temperatures could be a little lower. Predicted lows range from the upper 20s to mid-30s, except for upper 30s downtown and near the Chesapeake Bay.

These are not the first cold nights of autumn. Temperatures have already dipped into the 30s in much of the area this month, which has been colder than normal.

It’s been as cold as 36 in Baltimore, 34 at Dulles and 41 in Washington, based on measurements made at Reagan National Airport.

Historical dates of first fall freeze and how this year compares

The potential for freezing lows north and west of Washington is coming pretty close to average or a little early based on observations over the last 30 years.

Dulles, on average, sees its first freeze on Oct. 19. Baltimore, based on measurements made at BWI Marshall Airport, posts its first 32-degree low on Oct. 29.

In Washington, the average first freeze doesn’t come along until Nov. 11. But Reagan National Airport, where the District’s weather observations are made, is one of the last places in the region to experience freezing temperatures. This is mostly because it’s next to the Potomac River, which often helps keep temperatures milder than other spots.

Washington’s first freeze has come as early as Oct. 10, 1895, when temperatures were measured at 24th and M St. NW, and as late as Dec. 22, 2001 at Reagan National. The earliest first freeze at Reagan National occurred on Oct. 20, 1972.

Baltimore’s earliest first freeze came Oct. 4, 1974, and the latest Dec. 11, 1939, when its temperatures were measured downtown rather than at BWI Airport. At Dulles, freezes have come as early as Sept. 24 in 1974 and 1983, then as late as Nov. 11 in 2005.

Last year, Washington’s first freeze occurred on Nov. 17 while it happened in Dulles and Baltimore on Nov. 3 and Nov. 4, respectively.

Despite the somewhat early blast of chill this year, average first freezes have been arriving later over time because of human-caused climate change and urbanization.

Five decades ago, the city’s average first freeze came about 10 days earlier. A similar trend has been seen for the date of the last spring freeze. The District’s average final freeze has slipped from March 29 to March 24.

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