Frost Dates for 45039 — Maineville, Ohio

Half of springs at Milford, OH see their last 32°F night by April 23; only one in ten is past it by April 9, and one in ten still has one after May 8. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 3 20%, and after May 8 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 77% 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 6 one year in ten, and holds off past October 28 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, 10 days before the 32°F one. The freeze-free season lasts 177 days in a typical year, shorter than at 61% of the 148 Ohio stations; it reaches 193 days one year in ten and falls short of 158 one year in ten. On average 116 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 9 days longer, to about May 2, and return around October 9. Severe cold of 16°F or below comes every winter, usually between December 4 and March 11.

July is the warmest month at Milford, OH, averaging 87°F by day and 64°F at night; January is the coldest at 39°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 26% of years.

Warmth for growing adds up to 3,636 growing degree days a year (base 50°F), more than at 86% of the 148 Ohio stations. 36% of them (1,322) have built up by the end of June, and July adds the most, 787.

The nearest other station, Hamilton Butler Co Regional Airport, OH, 15 miles west of Maineville, has a last frost 1 day earlier (April 22), the same first-frost date, a season 1 day longer.

The first measurable snow (0.1 inch or more) in Maineville usually arrives around December 11, and the last of the season around March 13. Those are the middle dates across the winters of 1991–2020 at Kings Mills, OH, 2.5 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 41 days after the last snow.

ZIP 45039 is 10 miles from Milford, OH, which stands at 520 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 16 other ZIP codes share the station; its figures are presented in full for 45140 (Loveland). The 2023 USDA Plant Hardiness Zone Map lists ZIP 45039 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.