Richey, MT 59259 Frost Dates
59259, near Richey, MT: the frost window
Around 05/16 is the usual last spring frost, about 261 days away. Fall's first freeze usually shows up around 09/22, roughly 129 days after the last spring frost.
Zone 4a (-30 to -25°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 Richey, not a forecast for this year.
Stretching the season past the first frost
Richey'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
05/16 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 05/31 and only about 1 year in 10 sees frost after that.
Richey against the rest of the dataset
Richey's growing season runs about 129 days, ranking 38,515 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 146 of 392.
Learn more
Two guides worth reading on 59259: local microclimates, on what one yard in Richey can differ from the 59259 normal, and zone vs. frost date, on why Zone 4a and Richey's frost date answer different questions.