Twin Bridges, MT 59751 Frost Dates
59751, near Twin Bridges, MT: the frost window
Around 06/08 is the usual last spring frost, about 284 days away. Fall's first freeze usually shows up around 09/02, roughly 82 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Twin Bridges in Zone 5a (-20 to -15°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
Twin Bridges's growing season runs out in roughly 1 week — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 06/08 isn't a guarantee
06/08 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/22 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 07/01 and only about 1 year in 10 sees frost after that.
Twin Bridges against the rest of the dataset
About 82 days separate Twin Bridges's last and first frost, putting it 40,034 of 40,283 ZIP codes nationally. Within MT, it ranks 359 of 392.
Learn more
Two guides worth reading on 59751: the frost range, on how to read the range around Twin Bridges's dates instead of trusting one, and local microclimates, on what one yard in Twin Bridges can differ from the 59751 normal.