Janesville, WI 53512 Frost Dates
Janesville, WI: when does the frost end?
The last spring frost here typically falls around 05/01, about 246 days from today. Fall's first freeze usually shows up around 10/12, roughly 162 days after the last spring frost.
Zone 5b (-15 to -10°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
With roughly 6 weeks until Janesville's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/01 isn't a guarantee
05/01 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 05/16 and only about 1 year in 10 sees frost after that.
Janesville against the rest of the dataset
Janesville's growing season runs about 162 days, ranking 31,598 of 40,283 US ZIP codes measured here, longest to shortest. Within WI, it ranks 249 of 860.
Learn more
Before leaning on 53512's figures: the frost range explains how to read the range around Janesville's dates instead of trusting one, while local microclimates explains what one yard in Janesville can differ from the 53512 normal.