McLaughlin, SD 57642 Frost Dates
57642, near McLaughlin, SD: the frost window
Typically, the last spring freeze lands around 05/12, roughly 257 days out. Fall's first freeze usually shows up around 09/28, roughly 137 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 McLaughlin, not a forecast for this year.
Stretching the season past the first frost
McLaughlin'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.
How much risk comes with planting early here
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/02 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/25 and only about 1 year in 10 sees frost after that.
McLaughlin against the rest of the dataset
About 137 days separate McLaughlin's last and first frost, putting it 37,563 of 40,283 ZIP codes nationally. Within SD, it ranks 341 of 378.
Learn more
Two guides worth reading on 57642: local microclimates, on what one yard in McLaughlin can differ from the 57642 normal, and zone vs. frost date, on why Zone 4b and McLaughlin's frost date answer different questions.