Iron Junction, MN 55751 Frost Dates
55751, near Iron Junction, MN: the frost window
Around 05/12 is the usual last spring frost, about 257 days away. Fall's first freeze usually shows up around 10/01, roughly 141 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Iron Junction in Zone 3b (-35 to -30°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Iron Junction's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/12 isn't a guarantee
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/30 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/28 and only about 1 year in 10 sees frost after that.
Iron Junction against the rest of the dataset
At roughly 141 frost-free days, Iron Junction places 37,005 of 40,283 ZIP codes in this dataset. Within MN, it ranks 732 of 943.
Learn more
Two guides worth reading on 55751: the frost range, on how to read the range around Iron Junction's dates instead of trusting one, and local microclimates, on what one yard in Iron Junction can differ from the 55751 normal.