Frost Dates for 74331 — Afton, Oklahoma

Half of springs at Spavinaw, OK see their last 32°F night by April 7; only one in ten is past it by March 22, and one in ten still has one after April 24. Planting tender crops after April 14 leaves a 30% risk of a frost on them, after April 18 20%, and after April 24 10%. The 17 days between the even-odds date and the one-in-ten date is narrower than at 41% of the 114 Oklahoma stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 2 in half of years, as early as October 19 one year in ten, and holds off past November 17 one year in ten. A hard freeze of 28°F follows 8 days later, around November 10; in spring the one-in-ten date for 28°F is April 12, 12 days before the 32°F one. The freeze-free season lasts 209 days in a typical year, shorter than at 58% of the 114 Oklahoma stations; it reaches 229 days one year in ten and falls short of 187 one year in ten. On average 69 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 April 18, and return around October 25. Severe cold of 16°F or below comes every winter, usually between December 13 and February 25.

July is the warmest month at Spavinaw, OK, averaging 91°F by day and 71°F at night; January is the coldest at 48°F and 26°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 70% of years.

Warmth for growing adds up to 4,909 growing degree days a year (base 50°F), fewer than at 83% of the 114 Oklahoma stations. 37% of them (1,815) have built up by the end of June, and July adds the most, 966. Precipitation totals 46.6 inches a year, most in May (6.3") and least in January (2.3"); May to September bring 50% of it.

The nearest other station, Miami, OK, 19 miles north of Afton, has a last frost 1 day earlier (April 6), a first frost 6 days earlier (October 27), a season 6 days shorter.

The first measurable snow (0.1 inch or more) in Afton usually arrives around January 8, and the last of the season around February 9. Those are the middle dates across the winters of 1991–2020 at Spavinaw, OK, 17.3 miles away: half of years saw snow earlier, half later. Snow fell in 88% of those winters. The last 32°F night of spring typically comes 57 days after the last snow.

ZIP 74331 is 17 miles from Spavinaw, OK, which stands at 685 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 74301 (Vinita). The 2023 USDA Plant Hardiness Zone Map lists ZIP 74331 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.