Frost Dates for 57069 — Vermillion, South Dakota

Half of springs at Vermillion 2 SE, SD see their last 32°F night by May 3; only one in ten is past it by April 20, and one in ten still has one after May 16. Planting tender crops after May 9 leaves a 30% risk of a frost on them, after May 12 20%, and after May 16 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 43% of the 49 South Dakota stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 3 in half of years, as early as September 20 one year in ten, and holds off past October 17 one year in ten. A hard freeze of 28°F follows 12 days later, around October 15; in spring the one-in-ten date for 28°F is May 9, 7 days before the 32°F one. The freeze-free season lasts 153 days in a typical year, longer than at 67% of the 49 South Dakota stations; it reaches 171 days one year in ten and falls short of 133 one year in ten. On average 152 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 8 days longer, to about May 11, and return around September 25. Severe cold of 16°F or below comes every winter, usually between November 10 and March 26.

July is the warmest month at Vermillion 2 SE, SD, averaging 86°F by day and 63°F at night; January is the coldest at 31°F and 10°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 60% of years.

Warmth for growing adds up to 3,160 growing degree days a year (base 50°F), more than at 94% of the 49 South Dakota stations. 35% of them (1,096) have built up by the end of June, and July adds the most, 755. Precipitation totals 28.1 inches a year, most in June (4.3") and least in January (0.5"); May to September bring 64% of it.

The nearest other station, Centerville 6 SE, SD, 16 miles north of Vermillion, has a last frost 1 day earlier (May 2), a first frost 2 days earlier (October 1), a season 2 days shorter.

The first measurable snow (0.1 inch or more) in Vermillion usually arrives around November 11, and the last of the season around April 3. Those are the middle dates across the winters of 1991–2020 at Vermillion 2 SE, SD, 3.7 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 30 days after the last snow.

ZIP 57069 is 4 miles from Vermillion 2 SE, SD, which stands at 1,137 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 57069 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.