Frost Dates for 37692 — Unicoi, Tennessee

Half of springs at Erwin 1 W, TN see their last 32°F night by April 21; only one in ten is past it by April 4, and one in ten still has one after May 11. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 5 20%, and after May 11 10%. The 20 days between the even-odds date and the one-in-ten date is wider than at 95% of the 144 Tennessee stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 23 in half of years, as early as October 11 one year in ten, and holds off past November 4 one year in ten. A hard freeze of 28°F follows 9 days later, around November 1; in spring the one-in-ten date for 28°F is April 30, 11 days before the 32°F one. The freeze-free season lasts 183 days in a typical year, shorter than at 92% of the 144 Tennessee stations; it reaches 203 days one year in ten and falls short of 160 one year in ten. On average 98 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 May 3, and return around October 14. Severe cold of 16°F or below comes every winter, usually between December 9 and February 26.

July is the warmest month at Erwin 1 W, TN, averaging 85°F by day and 62°F at night; January is the coldest at 47°F and 25°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 29% of years.

Warmth for growing adds up to 3,607 growing degree days a year (base 50°F), fewer than at 94% of the 144 Tennessee stations. 36% of them (1,307) have built up by the end of June, and July adds the most, 738. Precipitation totals 47.0 inches a year, most in July (5.5") and least in October (2.5"); May to September bring 50% of it.

The nearest other station, Elizabethton, TN, 11 miles north of Unicoi and 233 feet lower, has a last frost 2 days earlier (April 19), a first frost 1 day later (October 24), a season 4 days longer.

The first measurable snow (0.1 inch or more) in Unicoi usually arrives around December 26, and the last of the season around March 4. Those are the middle dates across the winters of 1991–2020 at Erwin 1 W, TN, 7.7 miles away: half of years saw snow earlier, half later. Snow fell in 83% of those winters. The last 32°F night of spring typically comes 48 days after the last snow.

ZIP 37692 is 8 miles from Erwin 1 W, TN, which stands at 1,720 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 37659 (Jonesborough). The 2023 USDA Plant Hardiness Zone Map lists ZIP 37692 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.