Frost Dates for 45251 — Cincinnati, Ohio

Half of springs at Fairfield, OH see their last 32°F night by April 19; only one in ten is past it by April 2, and one in ten still has one after May 7. Planting tender crops after April 26 leaves a 30% risk of a frost on them, after May 1 20%, and after May 7 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 76% 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 23, 14 days before the 32°F one. The freeze-free season lasts 186 days in a typical year, longer than at 71% of the 148 Ohio stations; it reaches 206 days one year in ten and falls short of 164 one year in ten. On average 114 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 30, and return around October 12. Severe cold of 16°F or below comes every winter, usually between December 6 and March 4.

July is the warmest month at Fairfield, OH, averaging 87°F by day and 65°F at night; January is the coldest at 38°F and 21°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 20% of years.

Warmth for growing adds up to 3,663 growing degree days a year (base 50°F), more than at 88% of the 148 Ohio stations. 36% of them (1,315) have built up by the end of June, and July adds the most, 804. Precipitation totals 45.2 inches a year, most in April (4.9") and least in February (3.0"); May to September bring 44% of it.

The nearest other station, Cheviot, OH, 7 miles south of Cincinnati and 316 feet higher, has a last frost 2 days earlier (April 17), a first frost 4 days later (October 26), a season 5 days longer.

The first measurable snow (0.1 inch or more) in Cincinnati usually arrives around December 7, and the last of the season around March 16. Those are the middle dates across the winters of 1991–2020 at Cheviot, OH, 7.4 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 34 days after the last snow.

ZIP 45251 is 6 miles from Fairfield, OH, which stands at 575 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 45013 (Hamilton). The 2023 USDA Plant Hardiness Zone Map lists ZIP 45251 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.