Riverton, WY 82501 Frost Dates
82501, near Riverton, WY: the frost window
Around 05/12 is the usual last spring frost, about 257 days away. Fall's first freeze usually shows up around 09/24, roughly 132 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Riverton in Zone 5a (-20 to -15°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Riverton's growing season runs out in roughly 4 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 Riverton's last frost
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/26 and only about 1 year in 10 sees frost after that.
Riverton against the rest of the dataset
At roughly 132 frost-free days, Riverton places 38,177 of 40,283 ZIP codes in this dataset. Within WY, it ranks 58 of 192.
Learn more
Two guides worth reading on 82501: zone vs. frost date, on why Zone 5a and Riverton's frost date answer different questions, and the frost range, on how to read the range around Riverton's dates instead of trusting one.