Janesville, MN 56048 Frost Dates
56048, near Janesville, MN: the frost window
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 155 days after the last spring frost.
Zone 5a (-20 to -15°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Janesville, not a forecast for this year.
Stretching the season past the first frost
Janesville'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 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/17 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/14 and only about 1 year in 10 sees frost after that.
Janesville against the rest of the dataset
About 155 days separate Janesville's last and first frost, putting it 33,993 of 40,283 ZIP codes nationally. Within MN, it ranks 353 of 943.
Learn more
Two guides worth reading on 56048: the frost range, on how to read the range around Janesville's dates instead of trusting one, and local microclimates, on what one yard in Janesville can differ from the 56048 normal.