Frost Dates for 57369 — Platte, South Dakota

Half of springs at Academy 2NE, SD see their last 32°F night by April 30; only one in ten is past it by April 16, and one in ten still has one after May 14. Planting tender crops after May 5 leaves a 30% risk of a frost on them, after May 8 20%, and after May 14 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 8 in half of years, as early as September 24 one year in ten, and holds off past October 21 one year in ten. A hard freeze of 28°F follows 10 days later, around October 18; in spring the one-in-ten date for 28°F is May 4, 10 days before the 32°F one. The freeze-free season lasts 159 days in a typical year, longer than at 86% of the 49 South Dakota stations; it reaches 178 days one year in ten and falls short of 141 one year in ten. On average 167 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 9, and return around September 29. Severe cold of 16°F or below comes every winter, usually between November 13 and March 21.

July is the warmest month at Academy 2NE, SD, averaging 87°F by day and 63°F at night; January is the coldest at 30°F and 11°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 48% of years.

Warmth for growing adds up to 2,968 growing degree days a year (base 50°F), more than at 82% of the 49 South Dakota stations. 32% of them (938) have built up by the end of June, and July adds the most, 769. Precipitation totals 23.9 inches a year, most in June (3.9") and least in January (0.5"); May to September bring 67% of it.

The nearest other station, Pickstown, SD, 31 miles southeast of Platte and 191 feet lower, has the same 50% last-frost date, a first frost 5 days later (October 13), a season 6 days longer.

The first measurable snow (0.1 inch or more) in Platte usually arrives around November 6, and the last of the season around April 12. Those are the middle dates across the winters of 1991–2020 at Platte, SD, 4.1 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 18 days after the last snow.

ZIP 57369 is 9 miles from Academy 2NE, SD, which stands at 1,681 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 57369 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.