Frost Dates for 45458 — Dayton, Ohio

Half of springs at Dayton Wright Bros Airport, 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 6. Planting tender crops after April 25 leaves a 30% risk of a frost on them, after April 30 20%, and after May 6 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 92% of the 148 Ohio stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 26 in half of years, as early as October 13 one year in ten, and holds off past November 6 one year in ten. A hard freeze of 28°F follows 10 days later, around November 5; in spring the one-in-ten date for 28°F is April 21, 15 days before the 32°F one. The freeze-free season lasts 192 days in a typical year, longer than at 86% of the 148 Ohio stations; it reaches 211 days one year in ten and falls short of 169 one year in ten. On average 103 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 12 days longer, to about April 29, and return around October 17. Severe cold of 16°F or below comes every winter, usually between December 10 and March 3.

July is the warmest month at Dayton Wright Bros Airport, OH, averaging 86°F by day and 65°F at night; January is the coldest at 39°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 18% of years.

Warmth for growing adds up to 3,709 growing degree days a year (base 50°F), more than at 90% of the 148 Ohio stations. 37% of them (1,362) have built up by the end of June, and July adds the most, 789. Precipitation totals 40.9 inches a year, most in June (4.9") and least in February (2.3"); May to September bring 45% of it.

The nearest other station, Franklin, OH, 9 miles southwest of Dayton and 283 feet lower, has a last frost 7 days later (April 24), a first frost 7 days earlier (October 19), a season 14 days shorter.

The first measurable snow (0.1 inch or more) in Dayton usually arrives around December 3, and the last of the season around March 13. Those are the middle dates across the winters of 1991–2020 at Xenia 6 SSE, OH, 13.7 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 35 days after the last snow.

ZIP 45458 is 4 miles from Dayton Wright Bros Airport, OH, which stands at 962 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 45458 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.