First frost expected to be very late this year
(WHSV) - The first frost of the year typically happens by this point in October but nights have stayed mild so we haven’t seen one yet. By the looks of it, we will likely have to wait until at least the last week of October to have our first frost.
Every year is different as in 2020, the first front was very early on September 20th. We’ve come close a few nights this fall with temperatures in the 40s but the first frost has yet to happen.
So how do we get frost? Clear nights and light wind lead to cooler nights. With frost, the ground temperatures are actually below freezing while the air temperature is not. Clear nights allow for more cold air to radiate from the ground, forcing warm air above the surface. Light wind does stir this air around, allowing for more efficient cooling.
Temperatures need to be at least in the 30s. Typically with clear nights and light wind, temperatures at 35 to 39 degrees can cause frost. The closer the temperature is to freezing, the easier it is to form frost so if there isn’t quite a clear night or a light wind, frost still develops.
Elevation plays a factor as well. Warm air rises and cold air sinks, so lower elevations cool quicker. Lower elevations such as the Potomac Highlands and the Valley are more likely to have a lighter wind versus a mountain top.
Our average first frost is around October 10th in the Shenandoah Valley. So far this season, the coolest temperature Staunton has recorded is 41 degrees. Dale Enterprise and Woodstock have recorded temperatures as low as 43 degrees.
While a cold front will bring a big cool down for the weekend, it appears it won’t be cold enough to cause a frost. It appears that it will at least be until the last week of October.
In order for this season to set the record for the latest first frost ever, it would have to happen past November 4th.
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