St. Martin, MN 56372 Frost Dates
56372, near St. Martin, MN: the frost window
The last spring frost here typically falls around 05/03, about 248 days from today. Fall's first freeze usually shows up around 10/07, roughly 155 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 St. Martin, not a forecast for this year.
Stretching the season past the first frost
St. Martin's growing season runs out in roughly 6 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/03 isn't a guarantee
05/03 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/21 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/17 and only about 1 year in 10 sees frost after that.
St. Martin against the rest of the dataset
At roughly 155 frost-free days, St. Martin places 34,124 of 40,283 ZIP codes in this dataset. Within MN, it ranks 367 of 943.
Learn more
Two guides worth reading on 56372: local microclimates, on what one yard in St. Martin can differ from the 56372 normal, and zone vs. frost date, on why Zone 4b and St. Martin's frost date answer different questions.