Broadus, MT 59314 Frost Dates
59314, near Broadus, MT: the frost window
Typically, the last spring freeze lands around 05/14, roughly 259 days out. Fall's first freeze usually shows up around 09/28, roughly 134 days after the last spring frost.
Zone 4b (-25 to -20°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 Broadus, not a forecast for this year.
Stretching the season past the first frost
Broadus'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 05/14 isn't a guarantee
05/14 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/02 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/27 and only about 1 year in 10 sees frost after that.
Broadus against the rest of the dataset
At roughly 134 frost-free days, Broadus places 38,013 of 40,283 ZIP codes in this dataset. Within MT, it ranks 114 of 392.
Learn more
Two guides worth reading on 59314: local microclimates, on what one yard in Broadus can differ from the 59314 normal, and zone vs. frost date, on why Zone 4b and Broadus's frost date answer different questions.