Frost Dates for 46241 — Indianapolis, Indiana

Half of springs at Indianapolis, IN see their last 32°F night by April 15; only one in ten is past it by April 2, and one in ten still has one after May 2. Planting tender crops after April 21 leaves a 30% risk of a frost on them, after April 26 20%, and after May 2 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 66% of the 125 Indiana 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 7 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, 11 days before the 32°F one. The freeze-free season lasts 193 days in a typical year, longer than at 75% of the 125 Indiana stations; it reaches 212 days one year in ten and falls short of 171 one year in ten. On average 106 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 11 days longer, to about April 26, and return around October 17. Severe cold of 16°F or below comes every winter, usually between December 6 and March 3.

July is the warmest month at Indianapolis, IN, averaging 85°F by day and 66°F at night; January is the coldest at 36°F and 21°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 12% of years.

Warmth for growing adds up to 3,715 growing degree days a year (base 50°F), more than at 71% of the 125 Indiana stations. 36% of them (1,343) have built up by the end of June, and July adds the most, 800. Precipitation totals 43.6 inches a year, most in June (5.0") and least in February (2.4"); May to September bring 47% of it.

The nearest other station, Indianapolis Nwfo, IN, 3 miles southwest of Indianapolis, has a last frost 3 days earlier (April 12), a first frost 1 day later (October 27), a season 3 days longer.

The first measurable snow (0.1 inch or more) in Indianapolis usually arrives around November 24, and the last of the season around March 13. Those are the middle dates across the winters of 1991–2020 at Indianapolis, IN, 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 33 days after the last snow.

ZIP 46241 is 3 miles from Indianapolis, IN, which stands at 790 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 46241 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.