Rapid City, SD 57703 Frost Dates
Rapid City, SD: when does the frost end?
Around 05/12 is the usual last spring frost, about 257 days away. Fall's first freeze usually shows up around 10/01, roughly 139 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Rapid City 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
With roughly 5 weeks until Rapid City's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Rapid City's last frost
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/26 and only about 1 year in 10 sees frost after that.
Rapid City against the rest of the dataset
About 139 days separate Rapid City's last and first frost, putting it 37,204 of 40,283 ZIP codes nationally. Within SD, it ranks 313 of 378.
Learn more
Before leaning on 57703's figures: zone vs. frost date explains why Zone 5a and Rapid City's frost date answer different questions, while the frost range explains how to read the range around Rapid City's dates instead of trusting one.