Frost Dates for 35966 — Flat Rock, Alabama

Half of springs at Bridgeport 5 NW, AL see their last 32°F night by April 7; only one in ten is past it by March 18, and one in ten still has one after April 28. Planting tender crops after April 16 leaves a 30% risk of a frost on them, after April 21 20%, and after April 28 10%. The 21 days between the even-odds date and the one-in-ten date is wider than at 88% of the 115 Alabama stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by October 31 in half of years, as early as October 18 one year in ten, and holds off past November 14 one year in ten. A hard freeze of 28°F follows 10 days later, around November 10; 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 208 days in a typical year, shorter than at 90% of the 115 Alabama stations; it reaches 232 days one year in ten and falls short of 184 one year in ten. On average 79 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 19, and return around October 22. Severe cold of 16°F or below comes in 92% of winters, usually between December 31 and February 1.

July is the warmest month at Bridgeport 5 NW, AL, averaging 88°F by day and 68°F at night; January is the coldest at 48°F and 29°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 63% of years.

Warmth for growing adds up to 4,459 growing degree days a year (base 50°F), fewer than at 98% of the 115 Alabama stations. 38% of them (1,701) have built up by the end of June, and July adds the most, 856.

The nearest other station, Valley Head, AL, 16 miles south of Flat Rock and 457 feet higher, has a last frost 1 day later (April 8), a first frost 2 days earlier (October 29), a season 6 days shorter.

The first measurable snow (0.1 inch or more) in Flat Rock usually arrives around January 18, and the last of the season around February 13. Those are the middle dates across the winters of 1991–2020 at Valley Head, AL, 15.7 miles away: half of years saw snow earlier, half later. Snow fell in 91% of those winters. The last 32°F night of spring typically comes 53 days after the last snow.

ZIP 35966 is 15 miles from Bridgeport 5 NW, AL, which stands at 664 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 37347 (Jasper). The 2023 USDA Plant Hardiness Zone Map lists ZIP 35966 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.