Wilton, WI 54670 Frost Dates
Wilton, WI: when does the frost end?
Around 05/12 is the usual last spring frost, about 257 days away. Fall's first freeze usually shows up around 09/29, roughly 138 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Wilton in Zone 5a (-20 to -15°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 5 weeks until Wilton's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Wilton's last frost
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/28 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/26 and only about 1 year in 10 sees frost after that.
Wilton against the rest of the dataset
Wilton's growing season runs about 138 days, ranking 37,444 of 40,283 US ZIP codes measured here, longest to shortest. Within WI, it ranks 747 of 860.
Learn more
Before leaning on 54670's figures: local microclimates explains what one yard in Wilton can differ from the 54670 normal, while zone vs. frost date explains why Zone 5a and Wilton's frost date answer different questions.