Frost Dates for 47401 — Bloomington, Indiana

Half of springs at Bloomington Indiana Univ, IN see their last 32°F night by April 15; only one in ten is past it by March 31, and one in ten still has one after May 3. Planting tender crops after April 22 leaves a 30% risk of a frost on them, after April 28 20%, and after May 3 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 84% 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 11 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 9 days later, around November 4; in spring the one-in-ten date for 28°F is April 22, 11 days before the 32°F one. The freeze-free season lasts 192 days in a typical year, longer than at 74% of the 125 Indiana stations; it reaches 214 days one year in ten and falls short of 169 one year in ten. On average 109 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 13 days longer, to about April 28, and return around October 16. Severe cold of 16°F or below comes every winter, usually between December 8 and March 4.

July is the warmest month at Bloomington Indiana Univ, IN, averaging 85°F by day and 65°F at night; January is the coldest at 37°F and 21°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 87% of years and May still brings one in 15% of years.

Warmth for growing adds up to 3,624 growing degree days a year (base 50°F), more than at 65% of the 125 Indiana stations. 36% of them (1,318) have built up by the end of June, and July adds the most, 775. Precipitation totals 49.5 inches a year, most in May (5.4") and least in February (3.0"); May to September bring 46% of it.

The nearest other station, Bloomington Monroe Co Airport, IN, 6 miles west of Bloomington, has a last frost 2 days later (April 17), a first frost 4 days earlier (October 22), a season 7 days shorter.

The first measurable snow (0.1 inch or more) in Bloomington usually arrives around December 9, and the last of the season around March 5. Those are the middle dates across the winters of 1991–2020 at Bloomington Indiana Univ, IN, 3.2 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 47401 is 3 miles from Bloomington Indiana Univ, IN, which stands at 830 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 47401 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.