Ortonville, MN 56278 Frost Dates
Ortonville, MN: when does the frost end?
The last spring frost here typically falls around 05/02, about 247 days from today. Fall's first freeze usually shows up around 10/04, roughly 153 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Ortonville in Zone 4b (-25 to -20°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 5 weeks until Ortonville's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/20 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/15 and only about 1 year in 10 sees frost after that.
Ortonville against the rest of the dataset
Ortonville's growing season runs about 153 days, ranking 34,545 of 40,283 US ZIP codes measured here, longest to shortest. Within MN, it ranks 412 of 943.
Learn more
Before leaning on 56278's figures: zone vs. frost date explains why Zone 4b and Ortonville's frost date answer different questions, while the frost range explains how to read the range around Ortonville's dates instead of trusting one.