Hysham, MT 59024 Frost Dates
59024, near Hysham, MT: the frost window
The last spring frost here typically falls around 05/22, about 267 days from today. Fall's first freeze usually shows up around 09/22, roughly 121 days after the last spring frost.
Hysham sits in USDA Zone 4b (-25 to -20°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
Hysham'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 Hysham's last frost
05/22 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 06/07 and only about 1 year in 10 sees frost after that.
Hysham against the rest of the dataset
At roughly 121 frost-free days, Hysham places 39,049 of 40,283 ZIP codes in this dataset. Within MT, it ranks 210 of 392.
Learn more
Two guides worth reading on 59024: the frost range, on how to read the range around Hysham's dates instead of trusting one, and local microclimates, on what one yard in Hysham can differ from the 59024 normal.