St. Francis, SD 57572 Frost Dates
57572, near St. Francis, SD: the frost window
Typically, the last spring freeze lands around 05/10, roughly 255 days out. Fall's first freeze usually shows up around 09/29, roughly 141 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts St. Francis 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
St. Francis'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 05/10 isn't a guarantee
05/10 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/29 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/23 and only about 1 year in 10 sees frost after that.
St. Francis against the rest of the dataset
At roughly 141 frost-free days, St. Francis places 36,973 of 40,283 ZIP codes in this dataset. Within SD, it ranks 299 of 378.
Learn more
Two guides worth reading on 57572: zone vs. frost date, on why Zone 5a and St. Francis's frost date answer different questions, and the frost range, on how to read the range around St. Francis's dates instead of trusting one.