Geraldine, MT 59450 Frost Dates
59450, near Geraldine, MT: the frost window
The last spring frost here typically falls around 05/24, about 269 days from today. Fall's first freeze usually shows up around 09/21, roughly 119 days after the last spring frost.
Zone 4b (-25 to -20°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 Geraldine, not a forecast for this year.
Stretching the season past the first frost
Geraldine's growing season runs out in roughly 3 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
05/24 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/06 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/10 and only about 1 year in 10 sees frost after that.
Geraldine against the rest of the dataset
At roughly 119 frost-free days, Geraldine places 39,182 of 40,283 ZIP codes in this dataset. Within MT, it ranks 224 of 392.
Learn more
Two guides worth reading on 59450: zone vs. frost date, on why Zone 4b and Geraldine's frost date answer different questions, and the frost range, on how to read the range around Geraldine's dates instead of trusting one.