Frost Dates for 57625 — Eagle Butte, South Dakota

Half of springs at Dupree 15 SSE, SD see their last 32°F night by May 6; only one in ten is past it by April 24, and one in ten still has one after May 20. Planting tender crops after May 12 leaves a 30% risk of a frost on them, after May 16 20%, and after May 20 10%. The 14 days between the even-odds date and the one-in-ten date is wider than at 59% of the 49 South Dakota stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 2 in half of years, as early as September 20 one year in ten, and holds off past October 16 one year in ten. A hard freeze of 28°F follows 9 days later, around October 11; in spring the one-in-ten date for 28°F is May 10, 10 days before the 32°F one. The freeze-free season lasts 148 days in a typical year, shorter than at 51% of the 49 South Dakota stations; it reaches 166 days one year in ten and falls short of 130 one year in ten. On average 170 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 11 days longer, to about May 17, and return around September 25. Severe cold of 16°F or below comes every winter, usually between November 6 and April 1.

July is the warmest month at Dupree 15 SSE, SD, averaging 86°F by day and 61°F at night; January is the coldest at 28°F and 9°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 74% of years.

Warmth for growing adds up to 2,706 growing degree days a year (base 50°F), more than at 53% of the 49 South Dakota stations. 29% of them (789) have built up by the end of June, and July adds the most, 728. Precipitation totals 19.5 inches a year, most in May (3.5") and least in January (0.4"); May to September bring 67% of it.

The first measurable snow (0.1 inch or more) in Eagle Butte usually arrives around November 7, and the last of the season around April 4. Those are the middle dates across the winters of 1991–2020 at Eagle Butte, SD, 6.6 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 32 days after the last snow.

ZIP 57625 is 14 miles from Dupree 15 SSE, SD, which stands at 2,100 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 57625 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°C) over 1991–2020; a zone describes winter lows, not frost dates.