Sullivan, WI 53137 Frost Dates
Sullivan, WI: when does the frost end?
Around 05/03 is the usual last spring frost, about 248 days away. Fall's first freeze usually shows up around 10/09, roughly 157 days after the last spring frost.
Sullivan sits in USDA Zone 5b (-15 to -10°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
With roughly 6 weeks until Sullivan's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
05/03 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/21 and only about 1 year in 10 sees frost after that.
Sullivan against the rest of the dataset
At roughly 157 frost-free days, Sullivan places 33,411 of 40,283 ZIP codes in this dataset. Within WI, it ranks 401 of 860.
Learn more
Before leaning on 53137's figures: zone vs. frost date explains why Zone 5b and Sullivan's frost date answer different questions, while the frost range explains how to read the range around Sullivan's dates instead of trusting one.