Sun Prairie, WI 53783 Frost Dates
Sun Prairie, WI: when does the frost end?
Around 05/01 is the usual last spring frost, about 246 days away. Fall's first freeze usually shows up around 10/10, roughly 160 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 Sun Prairie, not a forecast for this year.
Stretching the season past the first frost
With roughly 6 weeks until Sun Prairie'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 04/16 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.
Sun Prairie against the rest of the dataset
At roughly 160 frost-free days, Sun Prairie places 32,229 of 40,283 ZIP codes in this dataset. Within WI, it ranks 335 of 860.
Learn more
Before leaning on 53783's figures: local microclimates explains what one yard in Sun Prairie can differ from the 53783 normal, while zone vs. frost date explains why Zone 5b and Sun Prairie's frost date answer different questions.