Rockham, SD 57470 Frost Dates
Rockham, 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 145 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Rockham 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 Rockham's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Rockham's last frost
05/08 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 05/21 and only about 1 year in 10 sees frost after that.
Rockham against the rest of the dataset
Rockham's growing season runs about 145 days, ranking 36,318 of 40,283 US ZIP codes measured here, longest to shortest. Within SD, it ranks 254 of 378.
Learn more
Before leaning on 57470's figures: zone vs. frost date explains why Zone 4b and Rockham's frost date answer different questions, while the frost range explains how to read the range around Rockham's dates instead of trusting one.