Frost Dates for 45054 — Oregonia, Ohio

Half of springs at WFO Wilmington, OH see their last 32°F night by April 17; only one in ten is past it by April 3, and one in ten still has one after May 4. Planting tender crops after April 23 leaves a 30% risk of a frost on them, after April 27 20%, and after May 4 10%. The 17 days between the even-odds date and the one-in-ten date is narrower than at 24% of the 148 Ohio stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 22 in half of years, as early as October 9 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 10 days later, around November 1; in spring the one-in-ten date for 28°F is April 20, 14 days before the 32°F one. The freeze-free season lasts 187 days in a typical year, longer than at 75% of the 148 Ohio stations; it reaches 206 days one year in ten and falls short of 167 one year in ten. On average 105 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 28, and return around October 11. Severe cold of 16°F or below comes every winter, usually between December 7 and March 6.

July is the warmest month at WFO Wilmington, OH, averaging 85°F by day and 64°F at night; January is the coldest at 38°F and 22°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 15% of years.

Warmth for growing adds up to 3,605 growing degree days a year (base 50°F), more than at 84% of the 148 Ohio stations. 37% of them (1,348) have built up by the end of June, and July adds the most, 764. Precipitation totals 44.7 inches a year, most in May (4.8") and least in February (2.9"); May to September bring 44% of it.

The nearest other station, Cincinnati, OH, 13 miles east of Oregonia, has a last frost 2 days later (April 19), the same first-frost date, a season 2 days shorter.

The first measurable snow (0.1 inch or more) in Oregonia usually arrives around November 21, and the last of the season around March 26. Those are the middle dates across the winters of 1991–2020 at WFO Wilmington, OH, 12.9 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 22 days after the last snow.

ZIP 45054 is 13 miles from WFO Wilmington, OH, which stands at 1,053 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 45113 (Clarksville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 45054 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.