Leola, SD 57456 Frost Dates
57456, near Leola, SD: the frost window
Around 05/09 is the usual last spring frost, about 254 days away. Fall's first freeze usually shows up around 09/28, roughly 141 days after the last spring frost.
Zone 4b (-25 to -20°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Leola, not a forecast for this year.
Stretching the season past the first frost
Leola's growing season runs out in roughly 4 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/09 isn't a guarantee
05/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/28 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.
Leola against the rest of the dataset
Leola's growing season runs about 141 days, ranking 36,974 of 40,283 US ZIP codes measured here, longest to shortest. Within SD, it ranks 300 of 378.
Learn more
Two guides worth reading on 57456: local microclimates, on what one yard in Leola can differ from the 57456 normal, and zone vs. frost date, on why Zone 4b and Leola's frost date answer different questions.