West Union, MN 56389 Frost Dates
56389, near West Union, MN: the frost window
Around 05/13 is the usual last spring frost, about 258 days away. Fall's first freeze usually shows up around 09/27, roughly 134 days after the last spring frost.
West Union sits in USDA Zone 4b (-25 to -20°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
West Union's growing season runs out in roughly 4 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/13 isn't a guarantee
05/13 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/01 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.
West Union against the rest of the dataset
About 134 days separate West Union's last and first frost, putting it 38,031 of 40,283 ZIP codes nationally. Within MN, it ranks 821 of 943.
Learn more
Two guides worth reading on 56389: zone vs. frost date, on why Zone 4b and West Union's frost date answer different questions, and the frost range, on how to read the range around West Union's dates instead of trusting one.