Mackay, ID 83251 Frost Dates
Frost dates for Mackay, ID, ZIP 83251
Around 05/22 is the usual last spring frost, about 267 days away. The first fall frost typically arrives around 09/22, about 119 frost-free days later.
The USDA Plant Hardiness Zone Map puts Mackay in Zone 5a (-20 to -15°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 5a around Mackay has about 4 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 05/22 isn't a guarantee
05/22 is the middle of 30 years of NOAA records, not a promise. Plant by 05/05 and you're betting against frost in roughly 9 years out of 10. 06/09 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Mackay compares
At roughly 119 frost-free days, Mackay places 39,162 of 40,283 ZIP codes in this dataset. Within ID, it ranks 223 of 320.
Learn more
the frost range explains how to read the range around Mackay's dates instead of trusting one, and local microclimates explains what one yard in Mackay can differ from the 83251 normal.