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Autumn is here - first frosts in the U.S.

07:45 PM
September 21, 2025

Meteorological autumn
The average first frosts in the U.S.

First frosts can begin in September as autumn temps move in.First frosts can begin in September as autumn temps move in.

Now that Meteorological Autumn is here, and soon the Autumnal Equinox, it is time to be thinking about the upcoming first frosts. For gardeners, farmers, and those who enjoy the fresh air of Fall, this will be welcome information.

September

As expected, those in the North are usually the first to experience frosty mornings. Early-to-mid September is usually the time when frost forms on the ground in areas in North Dakota, Wyoming, Montana, and Maine. The earliest is usually Caribou, Maine, around the Autumnal Equinox, but cooler air can make it in earlier at times.

October

At this time, we usually see cozy sweaters being worn, pumpkin-spice-flavored everything, and even the Halloween candy being stocked to the max in stores. Major cities that will see the ice crystals forming on the shoots of grass usually in October include Boise, Idaho, Denver, Milwaukee, Wis., Cleveland, and Providence, R.I..

November

The leaves have changed colors of red, gold, and yellow and have been falling into crunchy piles on the ground by November. Residents across the central and southern Plains, the Mid-Atlantic, the Tennessee and middle Mississippi valleys will notice the formation of the brittle ice on the fields as temperatures drop into the 30s and 40s in the night.

December

The Pacific Northwest, northern California, the Southwest, the lower Mississippi Valley, and eastward over to the Southeast Coast are usually the final areas to see frost as cooler air settles into the U.S. By this time, many holiday celebrations are taking place and residents in cities like Seattle, Jacksonville, Fla., and Houston, Texas, are bundling up for the coming cooler days.

Becca Parker
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