Idaho Falls, ID 83402 Frost Dates
Frost dates for Idaho Falls, ID, ZIP 83402
The last spring frost here typically falls around 05/23, about 268 days from today. The first fall frost typically arrives around 09/20, about 114 frost-free days later.
Idaho Falls 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 Idaho Falls has about 3 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 Idaho Falls's last frost
05/23 is the middle of 30 years of NOAA records, not a promise. Plant by 05/07 and you're betting against frost in roughly 9 years out of 10. 06/13 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Idaho Falls compares
Idaho Falls's growing season runs about 114 days, ranking 39,348 of 40,283 US ZIP codes measured here, longest to shortest. Within ID, it ranks 230 of 320.
Learn more
the frost range explains how to read the range around Idaho Falls's dates instead of trusting one, and local microclimates explains what one yard in Idaho Falls can differ from the 83402 normal.