Letcher, SD 57359 Frost Dates
Letcher, SD: when does the frost end?
Typically, the last spring freeze lands around 04/27, roughly 242 days out. Fall's first freeze usually shows up around 10/11, roughly 167 days after the last spring frost.
Zone 5a (-20 to -15°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 Letcher, not a forecast for this year.
Stretching the season past the first frost
With roughly 6 weeks until Letcher's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Letcher's last frost
04/27 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/12 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/10 and only about 1 year in 10 sees frost after that.
Letcher against the rest of the dataset
Letcher's growing season runs about 167 days, ranking 30,219 of 40,283 US ZIP codes measured here, longest to shortest. Within SD, it ranks 5 of 378.
Learn more
Before leaning on 57359's figures: local microclimates explains what one yard in Letcher can differ from the 57359 normal, while zone vs. frost date explains why Zone 5a and Letcher's frost date answer different questions.