Frost Dates for 37846 — Philadelphia, Tennessee

Half of springs at Decatur 7NE, TN see their last 32°F night by April 10; only one in ten is past it by March 24, and one in ten still has one after April 28. Planting tender crops after April 18 leaves a 30% risk of a frost on them, after April 22 20%, and after April 28 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 67% of the 144 Tennessee stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 27 in half of years, as early as October 14 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 5; in spring the one-in-ten date for 28°F is April 16, 12 days before the 32°F one. The freeze-free season lasts 199 days in a typical year, shorter than at 64% of the 144 Tennessee stations; it reaches 221 days one year in ten and falls short of 177 one year in ten. On average 99 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 14 days longer, to about April 24, and return around October 19. Severe cold of 16°F or below comes in 96% of winters, usually between December 24 and February 11.

July is the warmest month at Decatur 7NE, TN, averaging 89°F by day and 67°F at night; January is the coldest at 48°F and 28°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 4,386 growing degree days a year (base 50°F), fewer than at 58% of the 144 Tennessee stations. 37% of them (1,632) have built up by the end of June, and July adds the most, 869. Precipitation totals 57.6 inches a year, most in December (5.7") and least in October (3.2"); May to September bring 39% of it.

The nearest other station, Kingston, TN, 13 miles north of Philadelphia, has a last frost 7 days earlier (April 3), a first frost 8 days later (November 4), a season 16 days longer.

The first measurable snow (0.1 inch or more) in Philadelphia usually arrives around January 17, and the last of the season around February 4. Those are the middle dates across the winters of 1991–2020 at Decatur 7NE, TN, 11.9 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 65 days after the last snow.

ZIP 37846 is 12 miles from Decatur 7NE, TN, which stands at 750 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 37874 (Sweetwater). The 2023 USDA Plant Hardiness Zone Map lists ZIP 37846 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.