Grenville, SD 57239 Frost Dates
57239, near Grenville, SD: the frost window
Typically, the last spring freeze lands around 05/01, roughly 246 days out. Fall's first freeze usually shows up around 10/12, roughly 164 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Grenville in Zone 4b (-25 to -20°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
Grenville'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.
How much risk comes with planting early here
05/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/17 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/12 and only about 1 year in 10 sees frost after that.
Grenville against the rest of the dataset
At roughly 164 frost-free days, Grenville places 31,265 of 40,283 ZIP codes in this dataset. Within SD, it ranks 22 of 378.
Learn more
Two guides worth reading on 57239: the frost range, on how to read the range around Grenville's dates instead of trusting one, and local microclimates, on what one yard in Grenville can differ from the 57239 normal.