Castlewood, SD 57223 Frost Dates
Castlewood, SD: when does the frost end?
Around 05/06 is the usual last spring frost, about 251 days away. Fall's first freeze usually shows up around 10/01, roughly 145 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Castlewood in Zone 4a (-30 to -25°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 Castlewood's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
05/06 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/25 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/20 and only about 1 year in 10 sees frost after that.
Castlewood against the rest of the dataset
At roughly 145 frost-free days, Castlewood places 36,250 of 40,283 ZIP codes in this dataset. Within SD, it ranks 237 of 378.
Learn more
Before leaning on 57223's figures: the frost range explains how to read the range around Castlewood's dates instead of trusting one, while local microclimates explains what one yard in Castlewood can differ from the 57223 normal.