Rapid City, SD 57701 Frost Dates
57701, near Rapid City, SD: the frost window
Typically, the last spring freeze lands around 05/03, roughly 248 days out. Fall's first freeze usually shows up around 10/08, roughly 157 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Rapid City in Zone 5b (-15 to -10°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
Rapid City'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
05/03 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/20 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/17 and only about 1 year in 10 sees frost after that.
Rapid City against the rest of the dataset
At roughly 157 frost-free days, Rapid City places 33,202 of 40,283 ZIP codes in this dataset. Within SD, it ranks 65 of 378.
Learn more
Two guides worth reading on 57701: zone vs. frost date, on why Zone 5b and Rapid City's frost date answer different questions, and the frost range, on how to read the range around Rapid City's dates instead of trusting one.