Shawano, WI 54166 Frost Dates
54166, near Shawano, WI: the frost window
Typically, the last spring freeze lands around 05/09, roughly 254 days out. Fall's first freeze usually shows up around 10/02, roughly 144 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 Shawano, not a forecast for this year.
Stretching the season past the first frost
Shawano'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 05/09 isn't a guarantee
05/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/26 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/24 and only about 1 year in 10 sees frost after that.
Shawano against the rest of the dataset
At roughly 144 frost-free days, Shawano places 36,350 of 40,283 ZIP codes in this dataset. Within WI, it ranks 665 of 860.
Learn more
Two guides worth reading on 54166: zone vs. frost date, on why Zone 5a and Shawano's frost date answer different questions, and the frost range, on how to read the range around Shawano's dates instead of trusting one.