Frost Dates for 37813 — Morristown, Tennessee

Half of springs at Morristown Radio Wcrk, TN see their last 32°F night by April 10; only one in ten is past it by March 25, and one in ten still has one after April 26. Planting tender crops after April 16 leaves a 30% risk of a frost on them, after April 20 20%, and after April 26 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 53% of the 144 Tennessee stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 28 in half of years, as early as October 16 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 9 days later, around November 6; in spring the one-in-ten date for 28°F is April 14, 12 days before the 32°F one. The freeze-free season lasts 201 days in a typical year, shorter than at 58% of the 144 Tennessee stations; it reaches 221 days one year in ten and falls short of 181 one year in ten. On average 84 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 22, and return around October 20. Severe cold of 16°F or below comes in 99% of winters, usually between December 23 and February 13.

July is the warmest month at Morristown Radio Wcrk, TN, averaging 86°F by day and 67°F at night; January is the coldest at 46°F and 27°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 75% of years.

Warmth for growing adds up to 4,129 growing degree days a year (base 50°F), fewer than at 74% of the 144 Tennessee stations. 38% of them (1,549) have built up by the end of June, and July adds the most, 826. Precipitation totals 48.2 inches a year, most in March (4.9") and least in October (2.8"); May to September bring 40% of it.

The nearest other station, Morristown WFO, TN, 7 miles west of Morristown, has a last frost 10 days earlier (March 31), a first frost 7 days later (November 4), a season 16 days longer.

The first measurable snow (0.1 inch or more) in Morristown usually arrives around December 29, and the last of the season around March 1. Those are the middle dates across the winters of 1991–2020 at Morristown Radio Wcrk, TN, 3.5 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 40 days after the last snow.

ZIP 37813 is 4 miles from Morristown Radio Wcrk, TN, which stands at 1,344 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 37814 (Morristown). The 2023 USDA Plant Hardiness Zone Map lists ZIP 37813 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.