Greybull, WY 82426 Frost Dates
Frost dates for Greybull, WY, ZIP 82426
Around 05/11 is the usual last spring frost, about 256 days away. The first fall frost typically arrives around 09/23, about 133 frost-free days later.
Zone 4b (-25 to -20°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 Greybull, not a forecast for this year.
What to do before the first frost
Zone 4b around Greybull 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.
How much risk comes with planting early here
05/11 is the middle of 30 years of NOAA records, not a promise. Plant by 04/30 and you're betting against frost in roughly 9 years out of 10. 05/24 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Greybull compares
About 133 days separate Greybull's last and first frost, putting it 38,070 of 40,283 ZIP codes nationally. Within WY, it ranks 48 of 192.
Learn more
the frost range explains how to read the range around Greybull's dates instead of trusting one, and local microclimates explains what one yard in Greybull can differ from the 82426 normal.