Janesville, WI 53548 Frost Dates
When can you plant in Janesville, WI?
Around 05/01 is the usual last spring frost, about 246 days away. The first fall frost typically arrives around 10/12, about 162 frost-free days later.
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.
What to do before the first frost
About 6 weeks of growing season left in Janesville before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Janesville's last frost
05/01 is the middle of 30 years of NOAA records, not a promise. Plant by 04/17 and you're betting against frost in roughly 9 years out of 10. 05/16 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Janesville compares
Janesville's growing season runs about 162 days, ranking 31,601 of 40,283 US ZIP codes measured here, longest to shortest. Within WI, it ranks 252 of 860.
Learn more
the frost range covers how to read the range around Janesville's dates instead of trusting one. local microclimates covers what one yard in Janesville can differ from the 53548 normal.