Iron River, MI 49964 Frost Dates
Iron River, MI: when does the frost end?
Around 06/06 is the usual last spring frost, about 282 days away. Fall's first freeze usually shows up around 09/09, roughly 94 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Iron River in Zone 4a (-30 to -25°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
With roughly 2 weeks until Iron River's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 06/06 isn't a guarantee
06/06 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/23 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 07/07 and only about 1 year in 10 sees frost after that.
Iron River against the rest of the dataset
At roughly 94 frost-free days, Iron River places 39,825 of 40,283 ZIP codes in this dataset. Within MI, it ranks 1,148 of 1,153.
Learn more
Before leaning on 49964's figures: zone vs. frost date explains why Zone 4a and Iron River's frost date answer different questions, while the frost range explains how to read the range around Iron River's dates instead of trusting one.