Cascade, MT 59626 Frost Dates
59626, near Cascade, MT: the frost window
Typically, the last spring freeze lands around 05/21, roughly 266 days out. Fall's first freeze usually shows up around 09/15, roughly 115 days after the last spring frost.
Cascade 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
Cascade's growing season runs out in roughly 3 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
05/21 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/07 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/08 and only about 1 year in 10 sees frost after that.
Cascade against the rest of the dataset
At roughly 115 frost-free days, Cascade places 39,335 of 40,283 ZIP codes in this dataset. Within MT, it ranks 251 of 392.
Learn more
Two guides worth reading on 59626: zone vs. frost date, on why Zone 4b and Cascade's frost date answer different questions, and the frost range, on how to read the range around Cascade's dates instead of trusting one.