Cascade, MT 59648 Frost Dates
59648, near Cascade, MT: the frost window
Typically, the last spring freeze lands around 05/19, roughly 264 days out. Fall's first freeze usually shows up around 09/24, roughly 124 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Cascade in Zone 4b (-25 to -20°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
Cascade'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 Cascade's last frost
05/19 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/06 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
About 124 days separate Cascade's last and first frost, putting it 38,862 of 40,283 ZIP codes nationally. Within MT, it ranks 189 of 392.
Learn more
Two guides worth reading on 59648: 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.