Grand Marais, MN 55604 Frost Dates
Grand Marais, MN: when does the frost end?
Typically, the last spring freeze lands around 05/22, roughly 267 days out. Fall's first freeze usually shows up around 10/09, roughly 136 days after the last spring frost.
Grand Marais 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
With roughly 6 weeks until Grand Marais's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
05/22 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 06/18 and only about 1 year in 10 sees frost after that.
Grand Marais against the rest of the dataset
Grand Marais's growing season runs about 136 days, ranking 37,715 of 40,283 US ZIP codes measured here, longest to shortest. Within MN, it ranks 796 of 943.
Learn more
Before leaning on 55604's figures: local microclimates explains what one yard in Grand Marais can differ from the 55604 normal, while zone vs. frost date explains why Zone 3b and Grand Marais's frost date answer different questions.