Frost Dates for 57078 — Yankton, South Dakota

Half of springs at Yankton 2 E, SD see their last 32°F night by April 27; only one in ten is past it by April 13, and one in ten still has one after May 10. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 6 20%, and after May 10 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 11 in half of years, as early as September 27 one year in ten, and holds off past October 23 one year in ten. A hard freeze of 28°F follows 10 days later, around October 21; in spring the one-in-ten date for 28°F is May 2, 8 days before the 32°F one. The freeze-free season lasts 164 days in a typical year, longer than at 94% of the 49 South Dakota stations; it reaches 186 days one year in ten and falls short of 144 one year in ten. On average 158 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 9 days longer, to about May 6, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 14 and March 20.

July is the warmest month at Yankton 2 E, SD, averaging 87°F by day and 64°F at night; January is the coldest at 30°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 37% of years.

Warmth for growing adds up to 3,169 growing degree days a year (base 50°F), more than at 96% of the 49 South Dakota stations. 33% of them (1,056) have built up by the end of June, and July adds the most, 789. Precipitation totals 28.9 inches a year, most in June (4.0") and least in January (0.7"); May to September bring 60% of it.

The nearest other station, Crofton, NE, 11 miles southwest of Yankton and 220 feet higher, has a last frost 3 days later (April 30), a first frost 3 days earlier (October 8), a season 4 days shorter.

The first measurable snow (0.1 inch or more) in Yankton usually arrives around November 7, and the last of the season around April 14. Those are the middle dates across the winters of 1991–2020 at Crofton, NE, 11.4 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 13 days after the last snow.

ZIP 57078 is 2 miles from Yankton 2 E, SD, which stands at 1,180 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 57078 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.