Frost Dates for 74631 — Blackwell, Oklahoma

Half of springs at Blackwell 1SSW, OK see their last 32°F night by April 12; only one in ten is past it by March 26, and one in ten still has one after April 28. Planting tender crops after April 19 leaves a 30% risk of a frost on them, after April 23 20%, and after April 28 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 61% of the 114 Oklahoma stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 29 in half of years, as early as October 16 one year in ten, and holds off past November 11 one year in ten. A hard freeze of 28°F follows 8 days later, around November 6; in spring the one-in-ten date for 28°F is April 18, 10 days before the 32°F one. The freeze-free season lasts 199 days in a typical year, shorter than at 86% of the 114 Oklahoma stations; it reaches 220 days one year in ten and falls short of 178 one year in ten. On average 97 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 23, and return around October 20. Severe cold of 16°F or below comes every winter, usually between December 7 and February 27.

July is the warmest month at Blackwell 1SSW, OK, averaging 94°F by day and 69°F at night; January is the coldest at 47°F and 22°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 76% of years.

Warmth for growing adds up to 4,710 growing degree days a year (base 50°F), fewer than at 92% of the 114 Oklahoma stations. 36% of them (1,707) have built up by the end of June, and July adds the most, 978. Precipitation totals 38.8 inches a year, most in May (5.4") and least in January (1.3"); May to September bring 57% of it.

The nearest other station, Blackwell 4SSE Mesonet, OK, 4 miles southeast of Blackwell, has a last frost 4 days earlier (April 8), a first frost 2 days earlier (October 27), a season 2 days longer.

The first measurable snow (0.1 inch or more) in Blackwell usually arrives around December 22, and the last of the season around February 25. Those are the middle dates across the winters of 1991–2020 at Blackwell 1SSW, OK, 1.2 miles away: half of years saw snow earlier, half later. Snow fell in 95% of those winters. The last 32°F night of spring typically comes 46 days after the last snow.

ZIP 74631 is 1 mile from Blackwell 1SSW, OK, which stands at 1,033 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 74631 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.