Mount Vernon, SD 57363 Frost Dates
Mount Vernon, SD: when does the frost end?
Around 04/27 is the usual last spring frost, about 242 days away. Fall's first freeze usually shows up around 10/11, roughly 167 days after the last spring frost.
Mount Vernon sits in USDA Zone 5a (-20 to -15°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
With roughly 6 weeks until Mount Vernon's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Mount Vernon'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.
Mount Vernon against the rest of the dataset
Mount Vernon's growing season runs about 167 days, ranking 30,147 of 40,283 US ZIP codes measured here, longest to shortest. Within SD, it ranks 4 of 378.
Learn more
Before leaning on 57363's figures: zone vs. frost date explains why Zone 5a and Mount Vernon's frost date answer different questions, while the frost range explains how to read the range around Mount Vernon's dates instead of trusting one.