Rapid City, SD 57702 Frost Dates
When can you plant in Rapid City, SD?
Typically, the last spring freeze lands around 05/20, roughly 265 days out. The first fall frost typically arrives around 09/25, about 126 frost-free days later.
Zone 5a (-20 to -15°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 Rapid City, not a forecast for this year.
What to do before the first frost
About 4 weeks of growing season left in Rapid City before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
05/20 is the middle of 30 years of NOAA records, not a promise. Plant by 05/09 and you're betting against frost in roughly 9 years out of 10. 06/03 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Rapid City compares
About 126 days separate Rapid City's last and first frost, putting it 38,677 of 40,283 ZIP codes nationally. Within SD, it ranks 370 of 378.
Learn more
local microclimates covers what one yard in Rapid City can differ from the 57702 normal. zone vs. frost date covers why Zone 5a and Rapid City's frost date answer different questions.