Nisland, SD 57762 Frost Dates
Nisland, SD: when does the frost end?
Typically, the last spring freeze lands around 05/08, roughly 253 days out. Fall's first freeze usually shows up around 10/01, roughly 144 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Nisland in Zone 4b (-25 to -20°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 5 weeks until Nisland's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/08 isn't a guarantee
05/08 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/27 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/22 and only about 1 year in 10 sees frost after that.
Nisland against the rest of the dataset
Nisland's growing season runs about 144 days, ranking 36,463 of 40,283 US ZIP codes measured here, longest to shortest. Within SD, it ranks 261 of 378.
Learn more
Before leaning on 57762's figures: local microclimates explains what one yard in Nisland can differ from the 57762 normal, while zone vs. frost date explains why Zone 4b and Nisland's frost date answer different questions.