Frost Dates for 40456 — Mount Vernon, Kentucky

Half of springs at Mt Vernon, KY see their last 32°F night by April 18; only one in ten is past it by March 31, and one in ten still has one after May 6. Planting tender crops after April 25 leaves a 30% risk of a frost on them, after April 30 20%, and after May 6 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 54% of the 113 Kentucky stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 24 in half of years, as early as October 13 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 11 days later, around November 4; in spring the one-in-ten date for 28°F is April 21, 15 days before the 32°F one. The freeze-free season lasts 189 days in a typical year, shorter than at 63% of the 113 Kentucky stations; it reaches 211 days one year in ten and falls short of 167 one year in ten. On average 101 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 12 days longer, to about April 30, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 11 and February 28.

July is the warmest month at Mt Vernon, KY, averaging 84°F by day and 66°F at night; January is the coldest at 42°F and 25°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 88% of years and May still brings one in 19% of years.

Warmth for growing adds up to 3,839 growing degree days a year (base 50°F), fewer than at 63% of the 113 Kentucky stations. 37% of them (1,431) have built up by the end of June, and July adds the most, 781. Precipitation totals 51.4 inches a year, most in March (4.9") and least in September (3.5"); May to September bring 42% of it.

The nearest other station, Crab Orchard 6 N, KY, 10 miles northwest of Mount Vernon, has the same 50% last-frost date, the same first-frost date, a season 1 day shorter.

The first measurable snow (0.1 inch or more) in Mount Vernon usually arrives around December 22, and the last of the season around February 25. Those are the middle dates across the winters of 1991–2020 at Mt Vernon, KY, 1 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 52 days after the last snow.

ZIP 40456 is 1 mile from Mt Vernon, KY, which stands at 1,160 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 40456 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.