White Sulphur Springs, MT 59053 Frost Dates
59053, near White Sulphur Springs, MT: the frost window
Around 06/03 is the usual last spring frost, about 279 days away. Fall's first freeze usually shows up around 09/08, roughly 94 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts White Sulphur Springs 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
White Sulphur Springs's growing season runs out in roughly 2 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 06/03 isn't a guarantee
06/03 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/20 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/25 and only about 1 year in 10 sees frost after that.
White Sulphur Springs against the rest of the dataset
White Sulphur Springs's growing season runs about 94 days, ranking 39,837 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 330 of 392.
Learn more
Two guides worth reading on 59053: the frost range, on how to read the range around White Sulphur Springs's dates instead of trusting one, and local microclimates, on what one yard in White Sulphur Springs can differ from the 59053 normal.