Frost Dates for 46923 — Delphi, Indiana

Half of springs at Delphi 2 N, IN see their last 32°F night by April 22; only one in ten is past it by April 7, and one in ten still has one after May 6. Planting tender crops after April 28 leaves a 30% risk of a frost on them, after May 1 20%, and after May 6 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 89% of the 125 Indiana stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 17 in half of years, as early as October 3 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 13 days later, around October 30; in spring the one-in-ten date for 28°F is April 23, 13 days before the 32°F one. The freeze-free season lasts 179 days in a typical year, shorter than at 59% of the 125 Indiana stations; it reaches 199 days one year in ten and falls short of 157 one year in ten. On average 117 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 6. Severe cold of 16°F or below comes every winter, usually between December 1 and March 8.

July is the warmest month at Delphi 2 N, IN, averaging 85°F by day and 63°F at night; January is the coldest at 34°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 22% of years.

Warmth for growing adds up to 3,403 growing degree days a year (base 50°F), more than at 54% of the 125 Indiana stations. 37% of them (1,245) have built up by the end of June, and July adds the most, 741. Precipitation totals 39.0 inches a year, most in June (4.6") and least in February (1.8"); May to September bring 51% of it.

The nearest other station, Young America, IN, 16 miles east of Delphi and 217 feet higher, has a last frost 3 days later (April 25), the same first-frost date, a season 5 days shorter.

The first measurable snow (0.1 inch or more) in Delphi usually arrives around December 5, and the last of the season around March 7. Those are the middle dates across the winters of 1991–2020 at Delphi 2 N, IN, 1.4 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 46 days after the last snow.

ZIP 46923 is 1 mile from Delphi 2 N, IN, which stands at 556 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 47960 (Monticello). The 2023 USDA Plant Hardiness Zone Map lists ZIP 46923 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.