Frost Dates for 47620 — Mount Vernon, Indiana

Half of springs at Mt Vernon, IN see their last 32°F night by April 7; only one in ten is past it by March 25, and one in ten still has one after April 27. Planting tender crops after April 15 leaves a 30% risk of a frost on them, after April 20 20%, and after April 27 10%. The 20 days between the even-odds date and the one-in-ten date is the widest of the 125 Indiana stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 28 in half of years, as early as October 10 one year in ten, and holds off past November 10 one year in ten. A hard freeze of 28°F follows 10 days later, around November 7; in spring the one-in-ten date for 28°F is April 14, 13 days before the 32°F one. The freeze-free season lasts 202 days in a typical year, longer than at 90% of the 125 Indiana stations; it reaches 222 days one year in ten and falls short of 177 one year in ten. On average 86 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 14 days longer, to about April 21, and return around October 17. Severe cold of 16°F or below comes every winter, usually between December 11 and February 24.

July is the warmest month at Mt Vernon, IN, averaging 88°F by day and 67°F at night; January is the coldest at 42°F and 23°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 75% of years.

Warmth for growing adds up to 4,094 growing degree days a year (base 50°F), more than at 86% of the 125 Indiana stations. 37% of them (1,510) have built up by the end of June, and July adds the most, 845. Precipitation totals 46.6 inches a year, most in April (5.1") and least in February (2.9"); May to September bring 42% of it.

The nearest other station, Jt Myers Locks & Dam, IN, 12 miles southwest of Mount Vernon, has a last frost 2 days earlier (April 5), a first frost 3 days later (October 31), a season 7 days longer.

The first measurable snow (0.1 inch or more) in Mount Vernon usually arrives around December 29, and the last of the season around February 16. Those are the middle dates across the winters of 1991–2020 at Mt Vernon, IN, 0.9 miles away: half of years saw snow earlier, half later. Snow fell in 93% of those winters. The last 32°F night of spring typically comes 50 days after the last snow.

ZIP 47620 is under a mile from Mt Vernon, IN, which stands at 357 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 47620 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.