Frost advisory for some areas west of D.C. overnight, freeze warning for 1-81 corridor

The National Weather Service has issued frost advisories for Frederick (Md.), Fauquier and Loudoun counties due to temperatures forecast to drop into the mid-30s late tonight and Tuesday morning.

Further west, along the 1-81 corridor, including Hagerstown, Martinsburg, and Winchester, a freeze warning is in effect, as lows may dip into the low 30s.

Locations inside the beltway and to the east should stay mild enough to avoid frost (although Reagan National Airport could challenge its record low of 41 set in 1928), but if you live in colder sections of Montgomery and Fairfax counties and have sensitive vegetation/crops, you may wish to take some precautions as patchy frost is possible.

Here are a couple definitions worth reviewing if you have sensitive crops in the advisory or warning areas:

*  A frost advisory means that frost is possible. Sensitive outdoor plants may be killed if left uncovered.

* A freeze warning means sub-freezing temperatures are imminent or highly likely. These conditions will kill crops and other sensitive vegetation.

How to cover your crops? I’m not a gardening expert, but WiseGeek provides this advice:

…cover your plants before sunset. Wrap as breathable a material as possible around the plants — like burlap, linen, newspaper, or old bed sheets — then secure it against the wind with heavy rocks or clothespins. It’s best to avoid using plastic or vinyl sheets alone to protect plants from frost, since these materials can trap condensation inside, which can freeze and damage the plant. Plastic can also get very cold, and transfer that cold to the plant. If you do want to use plastic, put a fabric sheet underneath it.

For additional details, read the entire WiseGeek article and I’d welcome any advice from readers if they have tips.

Lastly, here are some model graphics simulating forecast lows tonight.  I’d go with a blend between the NAM and European models.

European model

NAM Model


GFS Model


Related: Late season frost or freeze possible Monday night in D.C.’s western suburbs

Jason is currently the Washington Post’s weather editor. A native Washingtonian, Jason has been a weather enthusiast since age 10.
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Jason Samenow · May 13, 2013

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