Frost advisories cover parts of the Ohio and Tennessee valleys as Monday lows dip into the 30s

Gardeners from Kentucky to northern Alabama have one more cold night to plan around. Frost Advisories were still in force on the afternoon of Nov. 8 for the Ohio and Tennessee valleys and parts of the Southeast, and overnight lows heading into Monday, Nov. 9, were forecast to drop into the 30s. The setup is a clear sky, light wind and dry air, the combination that lets surface temperatures slide below the thermometer reading at head height.

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A frost advisory is the National Weather Service’s lighter tier, issued when temperatures near 36 degrees can leave a coating of ice crystals on exposed surfaces without a full freeze.

The Weather Prediction Center’s Nov. 8 frost call

The National Weather Service’s Weather Prediction Center said in its short-range discussion, issued at 2:14 p.m. EST on Nov. 8, that Monday-morning lows would fall into the 30s after another chilly night and that the Frost Advisories remained in effect across the Ohio and Tennessee valleys and the Southeast. The same discussion, valid from 00Z Nov. 9 to 00Z Nov. 11, put daytime highs mostly in the 50s and 60s across the northern tier and in the 60s and 70s across the southern tier, so the afternoons are mild enough to hide how sharp the overnight drop is.

An earlier edition of the center’s discussion, posted at 3 a.m. EST, described frost and freeze advisories stretching from the Mid-South to the Ohio and Tennessee valleys, with lows expected near freezing. Outside the frost zone, the rest of the country was forecast mostly dry on Monday, apart from rain and higher-elevation snow in the Pacific Northwest and scattered showers in the Upper Great Lakes and interior Northeast, so the Ohio and Tennessee valleys have clear nights working against them and few clouds to hold in the day’s warmth.

Which states were under alerts before Monday

For a state-by-state picture, the FOX Forecast Center’s Nov. 7 frost and freeze report remains the most detailed. It counted more than 19 million Americans under Frost Advisories or Freeze Warnings for Sunday morning, in a zone from the heart of the Ohio Valley south and west into parts of Oklahoma, Arkansas, Tennessee and northern Alabama.

The forecast lows by Sunday daybreak in that report ran from the upper 20s to low 30s across Ohio, Kentucky, Indiana and Illinois, and from the low to mid 30s across the Mid-South and Ozarks, covering Arkansas, Oklahoma and Missouri. Northern Alabama was set for the mid to upper 30s, while middle and eastern Tennessee hovered near freezing. The Tennessee Valley and northern Alabama were expected to have the weekend’s coldest air, with widespread frost on lawns, vehicles and windshields. Drivers in those areas were looking at scraping glass before the first trip of the morning.

The Monday forecast in the center’s discussion speaks of lows in the 30s, a range that fits an advisory rather than the freeze warnings tied to temperatures at or below 32 degrees. Local offices decide the exact counties and hours for each advisory, so a resident should check the live list rather than assume a neighbor county is covered.

What frost does to gardens, and what protects them

Frost forms when moisture in the air deposits as ice on surfaces that have cooled below freezing, even when the air a few feet up reads in the mid-30s. Tender plants such as basil, impatiens and peppers take damage at that point, while hardy crops like kale and cabbage usually shrug it off. Bringing pots indoors, draping sheets or row cover over beds before dusk, and watering the soil during the afternoon, which lets it hold and release more heat overnight, are the standard ways to blunt a night like this one.

A late first freeze after a warm autumn

The cold comes unusually late. FOX noted that the first freeze is arriving after nearly 50 weather stations recorded their warmest start to autumn on record, a streak it tied to persistent upper-level ridging and El Nino. For tomato and pepper plants, annual flowers and anything in a pot on a porch, the first night below about 36 degrees is the one that ends the season.

The offices that cover the region were signaling the same pattern. The Nashville forecast office posted on Nov. 5 that cooler and drier weather was expected over the next week, with weekend lows below freezing in some spots. On Nov. 7 the Louisville office’s front page listed frost advisory and freeze warning links among its hazards.

What comes after Monday is a larger swing. FOX Weather’s outlook for the rest of the week expects a push of Canadian air that starts spreading across the eastern United States late Friday, with lows falling into the 20s in the Great Lakes, Ohio Valley and Northeast. The unresolved question for the Tennessee Valley is whether that later push brings a freeze warning, a step colder than the advisories now in effect. FOX called the larger pattern a split in national temperatures, with the West running 10 to 20 degrees above average while the East cools, and a region that has waited longer than usual for its first freeze now has one in sight.

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

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