Leonard, MN 56671 Frost Dates
56671, near Leonard, 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 10/04, roughly 142 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Leonard 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
Leonard'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 04/29 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/30 and only about 1 year in 10 sees frost after that.
Leonard against the rest of the dataset
Leonard's growing season runs about 142 days, ranking 36,852 of 40,283 US ZIP codes measured here, longest to shortest. Within MN, it ranks 709 of 943.
Learn more
Two guides worth reading on 56671: zone vs. frost date, on why Zone 3b and Leonard's frost date answer different questions, and the frost range, on how to read the range around Leonard's dates instead of trusting one.