Plain, WI 53577 Frost Dates
53577, near Plain, WI: the frost window
Around 04/30 is the usual last spring frost, about 245 days away. Fall's first freeze usually shows up around 10/09, roughly 161 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Plain 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
Plain's growing season runs out in roughly 6 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/30 isn't a guarantee
04/30 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/15 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/14 and only about 1 year in 10 sees frost after that.
Plain against the rest of the dataset
Plain's growing season runs about 161 days, ranking 32,117 of 40,283 US ZIP codes measured here, longest to shortest. Within WI, it ranks 330 of 860.
Learn more
Two guides worth reading on 53577: local microclimates, on what one yard in Plain can differ from the 53577 normal, and zone vs. frost date, on why Zone 5a and Plain's frost date answer different questions.