Introduction to Fall Freezes
Leaves are changing, and the first day of astronomical fall is next Monday, Sept. 22. Most of the country will begin to see cooler temperatures in the coming weeks, and some won’t have to wait long. Even though winter doesn’t begin until December, cold air and freezing temperatures arrive well before then for most of the U.S.
What You Need To Know
The Northern Plains and Intermountain West usually dip down below freezing before September is over. Interior New England and the Great Lakes also see freezing temperatures before most of the country. Cold air arrives in Florida, the Gulf Coast, and the Desert Southwest last.
Understanding the First Freeze
Winter arrives at the same time every year on the calendar, but not on your thermometer. Every year is different. The maps below give a good idea of when you can expect the first freeze where you live based on the 1991-2020 U.S. climate normals. The maps show the ‘median,’ or average date of the first freeze. This is when you could expect the first freeze to arrive during a ‘normal’ year. The next one shows the ‘earliest 10%’ which shows a scenario of when colder air arrives early, about once every 10 years. And the last map shows the ‘latest 10%,’ so during a warm year when cold air arrives late.
Regional Breakdown
Northeast
Most of the Northeast and New England see the first freeze before or during early fall, in September or early October. The mountains and high elevations across interior New England and the Adirondacks average freezing temperatures sometime in September, with the rest of the Northeast getting freezing cold sometime during October or early November.
Midwest
The Upper Midwest and Northern Plains also get in on the cold early. Around the Great Lakes and Dakotas, the first freeze typically arrives during September or early October. Further south the wait isn’t much longer. Freezing air usually arrives to the rest of the Midwest sometime before Halloween.
Northwest
There are many microclimates across the Northwest, so the arrival of cold air varies. Across the Rockies and Intermountain West, some areas experience cold year-round and as early as August and early September. The Pacific Northwest might not see freezing temperatures arrive until late October or November thanks to the maritime influence.
Southwest
The Southwest has a variety of climates as well, so the temperatures differ greatly during the fall and winter. The Desert Southwest and coastal California don’t see the arrival of cold air until late in the season, sometimes not until December. Once you get into the high desert and Southern Plains, it arrives much earlier, around October or early November.
Southeast
If you live in the Southeast, it still gets cold, especially away from the large bodies of water. In the Appalachians and areas away from the Gulf and Atlantic coast, freezing temperatures usually begin before Thanksgiving in late October or early November. The Gulf Coast and Florida, however, wait much longer, with freezing temperatures not arriving until late November or December. In South and Central Florida and southern Texas, freezing temperatures may never even arrive.
Conclusion
The first freeze of the fall season varies greatly across the United States, with some areas experiencing cold temperatures as early as September and others not until December. Understanding when the first freeze typically occurs in your area can help you prepare for the changing seasons.
FAQs
Q: When does the first freeze typically occur in the Northern Plains?
A: The first freeze in the Northern Plains usually occurs before September is over.
Q: Which regions experience the first freeze last?
A: Cold air arrives last in Florida, the Gulf Coast, and the Desert Southwest.
Q: How do the maps below determine the first freeze?
A: The maps show the ‘median,’ or average date of the first freeze, based on the 1991-2020 U.S. climate normals.
Q: What is the difference between the ‘earliest 10%’ and ‘latest 10%’ maps?
A: The ‘earliest 10%’ map shows a scenario of when colder air arrives early, about once every 10 years, while the ‘latest 10%’ map shows when cold air arrives late, during a warm year.
