Seneca, SD 57473 Frost Dates
When can you plant in Seneca, SD?
Typically, the last spring freeze lands around 05/14, roughly 259 days out. The first fall frost typically arrives around 09/29, about 138 frost-free days later.
Seneca 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
About 5 weeks of growing season left in Seneca before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Seneca's last frost
05/14 is the middle of 30 years of NOAA records, not a promise. Plant by 04/30 and you're betting against frost in roughly 9 years out of 10. 05/25 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Seneca compares
Seneca's growing season runs about 138 days, ranking 37,492 of 40,283 US ZIP codes measured here, longest to shortest. Within SD, it ranks 339 of 378.
Learn more
local microclimates covers what one yard in Seneca can differ from the 57473 normal. zone vs. frost date covers why Zone 4b and Seneca's frost date answer different questions.