Frost Dates for 32421 — Altha, Florida

Half of springs at Marianna Municipal Airport, FL see their last 32°F night by March 1; only one in ten is past it by February 2, and one in ten still has one after March 21. Planting tender crops after March 10 leaves a 30% risk of a frost on them, after March 15 20%, and after March 21 10%. The 20 days between the even-odds date and the one-in-ten date is narrower than at 79% of the 101 Florida stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 27 in half of years, as early as November 8 one year in ten, and holds off past December 28 one year in ten. A hard freeze of 28°F follows 25 days later, around December 22; in spring the one-in-ten date for 28°F is March 10, 11 days before the 32°F one. The freeze-free season lasts 270 days in a typical year, shorter than at 79% of the 102 Florida stations; it reaches 305 days one year in ten and falls short of 243 one year in ten. On average 22 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 15 days longer, to about March 16, and return around November 13. Nights of 24°F, cold enough to damage hardier plants, come in 73% of winters and 16°F in 7%.

July is the warmest month at Marianna Municipal Airport, FL, averaging 92°F by day and 73°F at night; January is the coldest at 63°F and 41°F. A freezing night is all but certain in January (a 90% chance or more). From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 83% of years and March still brings one in 50% of years.

Warmth for growing adds up to 6,933 growing degree days a year (base 50°F), fewer than at 83% of the 158 Florida stations. 43% of them (2,974) have built up by the end of June, and July adds the most, 1,014. Precipitation totals 51.2 inches a year, most in June (5.1") and least in October (3.1"); May to September bring 44% of it.

The nearest other station, Chipley, FL, 27 miles northwest of Altha, has a last frost 4 days later (March 5), a first frost 6 days earlier (November 21), a season 7 days shorter.

Measurable snow is rare here: only 0 of 23 winters from 1991 to 2020 recorded 0.1 inch or more at Chipley, FL, 27.5 miles away, so there is no typical first-snow date to plan around.

ZIP 32421 is 20 miles from Marianna Municipal Airport, FL, which stands at 113 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station; its figures are presented in full for 32446 (Marianna). The 2023 USDA Plant Hardiness Zone Map lists ZIP 32421 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°C) over 1991–2020; a zone describes winter lows, not frost dates.