Frost Dates for 37166 — Smithville, Tennessee

Half of springs at Smithville 2 SE, TN see their last 32°F night by April 18; only one in ten is past it by April 2, and one in ten still has one after May 2. Planting tender crops after April 23 leaves a 30% risk of a frost on them, after April 28 20%, and after May 2 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 95% of the 144 Tennessee stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 22 in half of years, as early as October 10 one year in ten, and holds off past November 4 one year in ten. A hard freeze of 28°F follows 10 days later, around November 1; in spring the one-in-ten date for 28°F is April 20, 12 days before the 32°F one. The freeze-free season lasts 187 days in a typical year, shorter than at 87% of the 144 Tennessee stations; it reaches 207 days one year in ten and falls short of 167 one year in ten. On average 102 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 12 days longer, to about April 30, and return around October 13. Severe cold of 16°F or below comes every winter, usually between December 10 and February 21.

July is the warmest month at Smithville 2 SE, TN, averaging 88°F by day and 66°F at night; January is the coldest at 47°F and 26°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 13% of years.

Warmth for growing adds up to 4,066 growing degree days a year (base 50°F), fewer than at 80% of the 144 Tennessee stations. 37% of them (1,519) have built up by the end of June, and July adds the most, 825. Precipitation totals 57.0 inches a year, most in March (5.7") and least in October (3.3"); May to September bring 41% of it.

The nearest other station, Lancaster Edgar Evins Marina, TN, 11 miles north of Smithville and 260 feet lower, has a last frost 15 days earlier (April 3), a first frost 13 days later (November 4), a season 28 days longer.

The first measurable snow (0.1 inch or more) in Smithville usually arrives around January 16, and the last of the season around February 17. Those are the middle dates across the winters of 1991–2020 at Smithville 2 SE, TN, 1.5 miles away: half of years saw snow earlier, half later. Snow fell in 75% of those winters. The last 32°F night of spring typically comes 60 days after the last snow.

ZIP 37166 is 2 miles from Smithville 2 SE, TN, which stands at 890 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 37166 in zone 7b, the band where the coldest night of the year averaged 5 to 10°F (-15.0 to -12.2°C) over 1991–2020; a zone describes winter lows, not frost dates.