Frankfort, SD 57440 Frost Dates
Frost dates for Frankfort, SD, ZIP 57440
The last spring frost here typically falls around 05/08, about 253 days from today. The first fall frost typically arrives around 10/01, about 145 frost-free days later.
Frankfort sits in USDA Zone 4b (-25 to -20°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 4b around Frankfort has about 5 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
How much risk comes with planting early here
05/08 is the middle of 30 years of NOAA records, not a promise. Plant by 04/25 and you're betting against frost in roughly 9 years out of 10. 05/21 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Frankfort compares
About 145 days separate Frankfort's last and first frost, putting it 36,300 of 40,283 ZIP codes nationally. Within SD, it ranks 248 of 378.
Learn more
zone vs. frost date explains why Zone 4b and Frankfort's frost date answer different questions, and the frost range explains how to read the range around Frankfort's dates instead of trusting one.