Madison, SD 57042 Frost Dates
Frost dates for Madison, SD, ZIP 57042
Around 05/05 is the usual last spring frost, about 250 days away. The first fall frost typically arrives around 09/30, about 148 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 Madison, not a forecast for this year.
What to do before the first frost
Zone 4b around Madison 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.
Why 05/05 isn't a guarantee
05/05 is the middle of 30 years of NOAA records, not a promise. Plant by 04/22 and you're betting against frost in roughly 9 years out of 10. 05/18 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Madison compares
About 148 days separate Madison's last and first frost, putting it 35,705 of 40,283 ZIP codes nationally. Within SD, it ranks 196 of 378.
Learn more
the frost range explains how to read the range around Madison's dates instead of trusting one, and local microclimates explains what one yard in Madison can differ from the 57042 normal.