Belle Fourche, SD 57717 Frost Dates
Belle Fourche, SD: when does the frost end?
Typically, the last spring freeze lands around 05/12, roughly 257 days out. Fall's first freeze usually shows up around 10/02, roughly 143 days after the last spring frost.
Zone 4b (-25 to -20°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Belle Fourche, not a forecast for this year.
Stretching the season past the first frost
With roughly 5 weeks until Belle Fourche'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
05/12 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 05/25 and only about 1 year in 10 sees frost after that.
Belle Fourche against the rest of the dataset
At roughly 143 frost-free days, Belle Fourche places 36,520 of 40,283 ZIP codes in this dataset. Within SD, it ranks 267 of 378.
Learn more
Before leaning on 57717's figures: the frost range explains how to read the range around Belle Fourche's dates instead of trusting one, while local microclimates explains what one yard in Belle Fourche can differ from the 57717 normal.