Mills, WY 82638 Frost Dates
Frost dates for Mills, WY, ZIP 82638
Around 05/30 is the usual last spring frost, about 275 days away. The first fall frost typically arrives around 09/22, about 115 frost-free days later.
Mills sits in USDA Zone 5a (-20 to -15°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 5a around Mills 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 05/30 isn't a guarantee
05/30 is the middle of 30 years of NOAA records, not a promise. Plant by 05/12 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 Mills compares
Mills's growing season runs about 115 days, ranking 39,308 of 40,283 US ZIP codes measured here, longest to shortest. Within WY, it ranks 119 of 192.
Learn more
the frost range explains how to read the range around Mills's dates instead of trusting one, and local microclimates explains what one yard in Mills can differ from the 82638 normal.