Frost Dates for 45011 — Hamilton, Ohio

Half of springs at Hamilton Butler Co Regional Airport, OH see their last 32°F night by April 22; only one in ten is past it by April 6, and one in ten still has one after May 10. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 4 20%, and after May 10 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 18 in half of years, as early as October 5 one year in ten, and holds off past October 29 one year in ten. A hard freeze of 28°F follows 9 days later, around October 27; in spring the one-in-ten date for 28°F is April 28, 12 days before the 32°F one. The freeze-free season lasts 178 days in a typical year, shorter than at 54% of the 148 Ohio stations; it reaches 198 days one year in ten and falls short of 157 one year in ten. On average 115 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 10 days longer, to about May 2, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 1 and March 7.

July is the warmest month at Hamilton Butler Co Regional Airport, OH, averaging 87°F by day and 64°F at night; January is the coldest at 40°F and 22°F. A freezing night is all but certain in every month from October 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 27% of years.

Warmth for growing adds up to 3,637 growing degree days a year (base 50°F), more than at 87% of the 148 Ohio stations. 37% of them (1,344) have built up by the end of June, and July adds the most, 792. Precipitation totals 41.5 inches a year, most in April (4.6") and least in February (2.4"); May to September bring 44% of it.

The nearest other station, Fairfield, OH, 5 miles southwest of Hamilton, has a last frost 3 days earlier (April 19), a first frost 4 days later (October 22), a season 8 days longer.

The first measurable snow (0.1 inch or more) in Hamilton usually arrives around December 14, and the last of the season around March 4. Those are the middle dates across the winters of 1991–2020 at Middletown, OH, 9.9 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 49 days after the last snow.

ZIP 45011 is 3 miles from Hamilton Butler Co Regional Airport, OH, which stands at 634 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 45011 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.