Blackfoot, ID 83221 Frost Dates
Frost dates for Blackfoot, ID, ZIP 83221
Around 05/05 is the usual last spring frost, about 250 days away. The first fall frost typically arrives around 10/03, about 149 frost-free days later.
Blackfoot sits in USDA Zone 5b (-15 to -10°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 5b around Blackfoot has about 5 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.
The actual range around Blackfoot's last frost
05/05 is the middle of 30 years of NOAA records, not a promise. Plant by 04/23 and you're betting against frost in roughly 9 years out of 10. 05/22 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Blackfoot compares
About 149 days separate Blackfoot's last and first frost, putting it 35,487 of 40,283 ZIP codes nationally. Within ID, it ranks 117 of 320.
Learn more
the frost range explains how to read the range around Blackfoot's dates instead of trusting one, and local microclimates explains what one yard in Blackfoot can differ from the 83221 normal.