Many areas from the Ohio Valley to the Deep South could see a first frost or freeze by Saturday

Forecasters at NOAA’s Weather Prediction Center wrote in their medium-range discussion, issued at 2:34 a.m. EST on Nov. 9, that many areas across the Ohio Valley, the Tennessee Valley and into portions of the Deep South will have the first frost or freeze of the season by Saturday morning, Nov. 14. The discussion covers the span from Nov. 12 to Nov. 16. Canadian air arriving from the north is the engine behind the change.

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Part of the region already had a taste of it. FOX Weather reported on Nov. 7 that more than 19 million Americans were under Frost Advisories or Freeze Warnings for a weekend of lows in the upper 20s to low 30s across Ohio, Kentucky, Indiana and Illinois, and it noted that nearly 50 weather stations had just recorded their warmest start to autumn on record, which had pushed back typical first-freeze dates in many places.

The Prediction Center’s Saturday morning call

The Weather Prediction Center’s forecast pages split the near term from the longer range. In the short-range discussion issued at 2:59 a.m. EST on Nov. 9, forecasters expected another chilly night across the Tennessee Valleys and into portions of the Southeast, with Frost Advisories already in effect that morning. The Day 3 to 7 discussion then pushed the same cold further south and east, and it named Saturday morning as the point by which the first frost or freeze would arrive for many areas.

The wording is deliberately broad. “Many areas” and “portions of the Deep South” mark out a region rather than a list of towns, and the discussion does not say which spots will dip to 32 degrees Fahrenheit and which will stop at frost. Local National Weather Service offices turn that regional signal into watches and warnings as the cold approaches, and in the Deep South the first of those products would typically be a Frost Advisory or Freeze Watch posted a day or two before Saturday.

Cold reaching the Gulf Coast and Florida by Sunday

In its late-week outlook, written by Kevin Fitzgerald, the FOX Forecast Center said temperatures would turn noticeably colder beginning Friday, with Canadian cold spreading across the eastern states from late that day and highs holding in the 30s or 40s from the Northeast through the Great Lakes and Ohio Valley. Lows were forecast to fall into the 20s in those northern areas.

The forecasters estimated that by Saturday more than 160 million Americans would be experiencing below-average temperatures, and they said the cold could reach the Gulf Coast and Florida by Sunday. That timing sits one day behind the Prediction Center’s Saturday frost call for the Ohio and Tennessee Valleys, which is the order a southward-moving front would produce.

The earlier FOX Weather report on the weekend frost described the same pattern in miniature. Alerts there extended into parts of Tennessee and northern Alabama, where lows in the mid to upper 30s were expected to be the coldest of that weekend, and the forecasters attributed the chill to short-term weather features rather than the El Nino that shapes the season.

The Tallahassee page adds a practical distinction. Frost can form at ground level even when the air temperature measured about 2 meters up sits slightly above freezing, because the ground and the air near it cool the most on calm, humid nights, while a Freeze Watch or Warning is tied to forecast temperatures of 32 degrees or lower for at least two hours. The office uses 25 degrees as its hard-freeze mark, a threshold that varies somewhat between offices.

Frost, freeze and the normal first-freeze calendar

The terms carry specific meanings. The National Weather Service office in Greenville-Spartanburg describes a Frost Advisory as an alert for significant frost with minimum temperatures of 33 to 36 degrees, issued up to 24 hours ahead when confidence is above 80 percent. A Freeze Watch comes up to 48 hours ahead at medium confidence, above 50 percent, of lows at or below 32 degrees, and a Freeze Warning means forecasters are highly confident of lows at or below 32 degrees during the growing season.

Averages show how early Saturday is for the Gulf states. The Tallahassee office’s frost and freeze page lists 1991 to 2020 first-frost and first-freeze dates of Nov. 10 and Nov. 25 for Tallahassee, Nov. 7 and Nov. 18 for Albany, Georgia, and Nov. 12 and Nov. 28 for Dothan, Alabama. A freeze on Nov. 14 along the northern Gulf would therefore arrive ahead of schedule at most of those sites, though frost alone would be close to normal.

The open question for gardeners and growers is how far south a freeze, as opposed to frost, will actually reach. The Climate Prediction Center’s 6 to 10 day outlook, updated on Nov. 9 for Nov. 15 to 19, will show whether the cold lingers once Saturday morning has passed.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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