Mills, WY 82605 Frost Dates
Frost dates for Mills, WY, ZIP 82605
Typically, the last spring freeze lands around 05/30, roughly 275 days out. The first fall frost typically arrives around 09/22, about 115 frost-free days later.
Zone 5a (-20 to -15°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Mills, not a forecast for this year.
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.
The actual range around Mills's last frost
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 39,306 of 40,283 US ZIP codes measured here, longest to shortest. Within WY, it ranks 117 of 192.
Learn more
zone vs. frost date explains why Zone 5a and Mills's frost date answer different questions, and the frost range explains how to read the range around Mills's dates instead of trusting one.