Altha, FL 32421 Frost Dates
Frost dates for Altha, FL, ZIP 32421
Typically, the last spring freeze lands around 03/01, roughly 185 days out. The first fall frost typically arrives around 11/27, about 270 frost-free days later.
The USDA Plant Hardiness Zone Map puts Altha in Zone 9a (20 to 25°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 9a around Altha has about 13 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 03/01 isn't a guarantee
03/01 is the middle of 30 years of NOAA records, not a promise. Plant by 02/02 and you're betting against frost in roughly 9 years out of 10. 03/21 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Altha compares
At roughly 270 frost-free days, Altha places 5,621 of 40,283 ZIP codes in this dataset. Within FL, it ranks 1,511 of 1,609.
Learn more
zone vs. frost date explains why Zone 9a and Altha's frost date answer different questions, and the frost range explains how to read the range around Altha's dates instead of trusting one.