Frost Dates for 45817 — Bluffton, Ohio

Half of springs at Pandora, OH see their last 32°F night by April 23; only one in ten is past it by April 10, and one in ten still has one after May 9. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 3 20%, and after May 9 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 53% 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 6 one year in ten, and holds off past November 4 one year in ten. A hard freeze of 28°F follows 11 days later, around November 2; in spring the one-in-ten date for 28°F is April 29, 10 days before the 32°F one. The freeze-free season lasts 180 days in a typical year, longer than at 50% of the 148 Ohio stations; it reaches 199 days one year in ten and falls short of 159 one year in ten. On average 124 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 3, and return around October 10. Severe cold of 16°F or below comes every winter, usually between December 4 and March 11.

July is the warmest month at Pandora, OH, averaging 84°F by day and 64°F at night; January is the coldest at 33°F and 19°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 28% of years.

Warmth for growing adds up to 3,272 growing degree days a year (base 50°F), more than at 55% of the 148 Ohio stations. 36% of them (1,165) have built up by the end of June, and July adds the most, 741. Precipitation totals 38.7 inches a year, most in May (4.4") and least in February (2.2"); May to September bring 50% of it.

The nearest other station, Lima Allen Co Airport, OH, 14 miles southwest of Bluffton and 205 feet higher, 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 Bluffton usually arrives around November 23, and the last of the season around March 27. Those are the middle dates across the winters of 1991–2020 at Pandora, OH, 5.4 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 27 days after the last snow.

ZIP 45817 is 5 miles from Pandora, OH, which stands at 770 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 45875 (Ottawa). The 2023 USDA Plant Hardiness Zone Map lists ZIP 45817 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.