Hardin, MT 59064 Frost Dates
59064, near Hardin, MT: the frost window
Around 05/12 is the usual last spring frost, about 257 days away. Fall's first freeze usually shows up around 09/25, roughly 136 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Hardin 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
Hardin'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.
How much risk comes with planting early here
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/30 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/26 and only about 1 year in 10 sees frost after that.
Hardin against the rest of the dataset
At roughly 136 frost-free days, Hardin places 37,681 of 40,283 ZIP codes in this dataset. Within MT, it ranks 93 of 392.
Learn more
Two guides worth reading on 59064: local microclimates, on what one yard in Hardin can differ from the 59064 normal, and zone vs. frost date, on why Zone 4b and Hardin's frost date answer different questions.