Rock Springs, WY 82901 Frost Dates
Frost dates for Rock Springs, WY, ZIP 82901
The last spring frost here typically falls around 05/24, about 269 days from today. The first fall frost typically arrives around 09/24, about 121 frost-free days later.
Zone 5b (-15 to -10°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 Rock Springs, not a forecast for this year.
What to do before the first frost
Zone 5b around Rock Springs 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
05/24 is the middle of 30 years of NOAA records, not a promise. Plant by 05/08 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 Rock Springs compares
About 121 days separate Rock Springs's last and first frost, putting it 38,989 of 40,283 ZIP codes nationally. Within WY, it ranks 91 of 192.
Learn more
local microclimates explains what one yard in Rock Springs can differ from the 82901 normal, and zone vs. frost date explains why Zone 5b and Rock Springs's frost date answer different questions.