Thermopolis, WY 82443 Frost Dates
82443, near Thermopolis, WY: the frost window
The last spring frost here typically falls around 05/05, about 250 days from today. Fall's first freeze usually shows up around 10/05, roughly 152 days after the last spring frost.
Thermopolis 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.
Stretching the season past the first frost
Thermopolis's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around Thermopolis's last frost
05/05 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/23 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/19 and only about 1 year in 10 sees frost after that.
Thermopolis against the rest of the dataset
About 152 days separate Thermopolis's last and first frost, putting it 34,764 of 40,283 ZIP codes nationally. Within WY, it ranks 3 of 192.
Learn more
Two guides worth reading on 82443: zone vs. frost date, on why Zone 5a and Thermopolis's frost date answer different questions, and the frost range, on how to read the range around Thermopolis's dates instead of trusting one.