Harrold, SD 57540 Frost Dates
When can you plant in Harrold, SD?
Around 05/12 is the usual last spring frost, about 257 days away. The first fall frost typically arrives around 10/01, about 142 frost-free days later.
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 Harrold, not a forecast for this year.
What to do before the first frost
About 5 weeks of growing season left in Harrold before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/12 isn't a guarantee
05/12 is the middle of 30 years of NOAA records, not a promise. Plant by 04/28 and you're betting against frost in roughly 9 years out of 10. 05/28 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Harrold compares
At roughly 142 frost-free days, Harrold places 36,844 of 40,283 ZIP codes in this dataset. Within SD, it ranks 288 of 378.
Learn more
local microclimates covers what one yard in Harrold can differ from the 57540 normal. zone vs. frost date covers why Zone 4b and Harrold's frost date answer different questions.