Ryegate, MT 59074 Frost Dates
59074, near Ryegate, MT: the frost window
Around 05/17 is the usual last spring frost, about 262 days away. Fall's first freeze usually shows up around 09/23, roughly 127 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Ryegate 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
Ryegate'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 Ryegate's last frost
05/17 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/03 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/30 and only about 1 year in 10 sees frost after that.
Ryegate against the rest of the dataset
Ryegate's growing season runs about 127 days, ranking 38,661 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 155 of 392.
Learn more
Two guides worth reading on 59074: the frost range, on how to read the range around Ryegate's dates instead of trusting one, and local microclimates, on what one yard in Ryegate can differ from the 59074 normal.