Iron Junction, MN 55738 Frost Dates
Frost dates for Iron Junction, MN, ZIP 55738
Around 06/05 is the usual last spring frost, about 281 days away. The first fall frost typically arrives around 09/08, about 93 frost-free days later.
Iron Junction 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.
What to do before the first frost
Zone 3b around Iron Junction has about 2 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
The actual range around Iron Junction's last frost
06/05 is the middle of 30 years of NOAA records, not a promise. Plant by 05/22 and you're betting against frost in roughly 9 years out of 10. 06/25 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Iron Junction compares
Iron Junction's growing season runs about 93 days, ranking 39,880 of 40,283 US ZIP codes measured here, longest to shortest. Within MN, it ranks 931 of 943.
Learn more
zone vs. frost date explains why Zone 3b and Iron Junction's frost date answer different questions, and the frost range explains how to read the range around Iron Junction's dates instead of trusting one.