Frost Dates for 40220 — Louisville, Kentucky

Half of springs at Louisville Bowman Field, KY see their last 32°F night by April 3; only one in ten is past it by March 18, and one in ten still has one after April 19. Planting tender crops after April 9 leaves a 30% risk of a frost on them, after April 14 20%, and after April 19 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 68% of the 113 Kentucky stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 3 in half of years, as early as October 21 one year in ten, and holds off past November 16 one year in ten. A hard freeze of 28°F follows 10 days later, around November 13; in spring the one-in-ten date for 28°F is April 5, 14 days before the 32°F one. The freeze-free season lasts 214 days in a typical year, longer than at 96% of the 113 Kentucky stations; it reaches 232 days one year in ten and falls short of 193 one year in ten. On average 80 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 16, and return around October 23. Severe cold of 16°F or below comes in 99% of winters, usually between December 23 and February 14.

July is the warmest month at Louisville Bowman Field, KY, averaging 88°F by day and 69°F at night; January is the coldest at 43°F and 27°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 57% of years.

Warmth for growing adds up to 4,455 growing degree days a year (base 50°F), more than at 83% of the 113 Kentucky stations. 38% of them (1,710) have built up by the end of June, and July adds the most, 887. Precipitation totals 48.3 inches a year, most in May (5.2") and least in January (3.3"); May to September bring 45% of it.

The nearest other station, Louisville International Airport, KY, 7 miles west of Louisville, has a last frost 3 days earlier (March 31), a first frost 4 days later (November 7), a season 8 days longer.

The first measurable snow (0.1 inch or more) in Louisville usually arrives around December 7, and the last of the season around March 8. Those are the middle dates across the winters of 1991–2020 at Louisville International Airport, KY, 6.8 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 26 days after the last snow.

ZIP 40220 is 2 miles from Louisville Bowman Field, KY, which stands at 540 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 12 other ZIP codes share the station; its figures are presented in full for 40299 (Louisville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 40220 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.