Janesville, WI 53545 Frost Dates
Janesville, WI: when does the frost end?
Typically, the last spring freeze lands around 05/01, roughly 246 days out. Fall's first freeze usually shows up around 10/12, roughly 162 days after the last spring frost.
Janesville sits in USDA Zone 5b (-15 to -10°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
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 31,599 of 40,283 US ZIP codes measured here, longest to shortest. Within WI, it ranks 250 of 860.
Learn more
Before leaning on 53545'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 53545 normal.