Grygla, MN 56724 Frost Dates
56724, near Grygla, MN: the frost window
Typically, the last spring freeze lands around 05/20, roughly 265 days out. Fall's first freeze usually shows up around 09/17, roughly 118 days after the last spring frost.
Grygla sits in USDA Zone 3b (-35 to -30°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Grygla'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.
Why 05/20 isn't a guarantee
05/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/05 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/03 and only about 1 year in 10 sees frost after that.
Grygla against the rest of the dataset
At roughly 118 frost-free days, Grygla places 39,238 of 40,283 ZIP codes in this dataset. Within MN, it ranks 891 of 943.
Learn more
Two guides worth reading on 56724: local microclimates, on what one yard in Grygla can differ from the 56724 normal, and zone vs. frost date, on why Zone 3b and Grygla's frost date answer different questions.