Heron Lake, MN 56137 Frost Dates
Heron Lake, MN: when does the frost end?
The last spring frost here typically falls around 04/30, about 245 days from today. Fall's first freeze usually shows up around 10/10, roughly 162 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Heron Lake in Zone 5a (-20 to -15°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 6 weeks until Heron Lake's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Heron Lake's last frost
04/30 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/15 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/13 and only about 1 year in 10 sees frost after that.
Heron Lake against the rest of the dataset
About 162 days separate Heron Lake's last and first frost, putting it 31,832 of 40,283 ZIP codes nationally. Within MN, it ranks 185 of 943.
Learn more
Before leaning on 56137's figures: zone vs. frost date explains why Zone 5a and Heron Lake's frost date answer different questions, while the frost range explains how to read the range around Heron Lake's dates instead of trusting one.