Ethan, SD 57334 Frost Dates
Ethan, SD: when does the frost end?
Typically, the last spring freeze lands around 04/30, roughly 245 days out. Fall's first freeze usually shows up around 10/05, roughly 159 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Ethan in Zone 5a (-20 to -15°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 Ethan's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/30 isn't a guarantee
04/30 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/16 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/13 and only about 1 year in 10 sees frost after that.
Ethan against the rest of the dataset
Ethan's growing season runs about 159 days, ranking 32,751 of 40,283 US ZIP codes measured here, longest to shortest. Within SD, it ranks 41 of 378.
Learn more
Before leaning on 57334's figures: the frost range explains how to read the range around Ethan's dates instead of trusting one, while local microclimates explains what one yard in Ethan can differ from the 57334 normal.