Highmore, SD 57346 Frost Dates
57346, near Highmore, SD: the frost window
The last spring frost here typically falls around 05/10, about 255 days from today. Fall's first freeze usually shows up around 09/29, roughly 140 days after the last spring frost.
Highmore 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.
Stretching the season past the first frost
Highmore's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/10 isn't a guarantee
05/10 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/29 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/24 and only about 1 year in 10 sees frost after that.
Highmore against the rest of the dataset
Highmore's growing season runs about 140 days, ranking 37,111 of 40,283 US ZIP codes measured here, longest to shortest. Within SD, it ranks 308 of 378.
Learn more
Two guides worth reading on 57346: zone vs. frost date, on why Zone 4b and Highmore's frost date answer different questions, and the frost range, on how to read the range around Highmore's dates instead of trusting one.