Frost Dates for 47872 — Rockville, Indiana

Half of springs at Rockville, IN see their last 32°F night by April 30; only one in ten is past it by April 14, and one in ten still has one after May 15. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 10 20%, and after May 15 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 70% of the 125 Indiana stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 12 in half of years, as early as September 30 one year in ten, and holds off past October 24 one year in ten. A hard freeze of 28°F follows 10 days later, around October 22; in spring the one-in-ten date for 28°F is May 5, 10 days before the 32°F one. The freeze-free season lasts 164 days in a typical year, shorter than at 98% of the 125 Indiana stations; it reaches 184 days one year in ten and falls short of 142 one year in ten. On average 111 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 10, and return around October 2. Severe cold of 16°F or below comes every winter, usually between November 25 and March 15.

July is the warmest month at Rockville, IN, averaging 86°F by day and 62°F at night; January is the coldest at 36°F and 17°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 47% of years.

Warmth for growing adds up to 3,402 growing degree days a year (base 50°F), more than at 54% of the 125 Indiana stations. 37% of them (1,248) have built up by the end of June, and July adds the most, 741. Precipitation totals 47.5 inches a year, most in June (5.5") and least in February (2.6"); May to September bring 47% of it.

The nearest other station, Greencastle 1 W, IN, 18 miles southeast of Rockville, has a last frost 3 days earlier (April 27), a first frost 3 days later (October 15), a season 5 days longer.

The first measurable snow (0.1 inch or more) in Rockville usually arrives around December 9, and the last of the season around March 1. Those are the middle dates across the winters of 1991–2020 at Rockville, IN, 2.7 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 60 days after the last snow.

ZIP 47872 is 3 miles from Rockville, IN, which stands at 689 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 47842 (Clinton). The 2023 USDA Plant Hardiness Zone Map lists ZIP 47872 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.