Sundance, WY 82712 Frost Dates
82712, near Sundance, WY: the frost window
Around 05/21 is the usual last spring frost, about 266 days away. Fall's first freeze usually shows up around 09/25, roughly 124 days after the last spring frost.
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 Sundance, not a forecast for this year.
Stretching the season past the first frost
Sundance'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.
Why 05/21 isn't a guarantee
05/21 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/09 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/05 and only about 1 year in 10 sees frost after that.
Sundance against the rest of the dataset
About 124 days separate Sundance's last and first frost, putting it 38,851 of 40,283 ZIP codes nationally. Within WY, it ranks 82 of 192.
Learn more
Two guides worth reading on 82712: the frost range, on how to read the range around Sundance's dates instead of trusting one, and local microclimates, on what one yard in Sundance can differ from the 82712 normal.