Frost Dates for 40258 — Louisville, Kentucky

Half of springs at Louisville International Airport, KY see their last 32°F night by March 31; only one in ten is past it by March 14, and one in ten still has one after April 16. Planting tender crops after April 4 leaves a 30% risk of a frost on them, after April 9 20%, and after April 16 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 7 in half of years, as early as October 28 one year in ten, and holds off past November 23 one year in ten. A hard freeze of 28°F follows 10 days later, around November 17; in spring the one-in-ten date for 28°F is April 3, 13 days before the 32°F one. The freeze-free season lasts 222 days in a typical year, longer than at 98% of the 113 Kentucky stations; it reaches 243 days one year in ten and falls short of 202 one year in ten. On average 74 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 11 days longer, to about April 11, and return around October 29. Severe cold of 16°F or below comes in 99% of winters, usually between December 28 and February 12.

July is the warmest month at Louisville International Airport, KY, averaging 89°F by day and 71°F at night; January is the coldest at 44°F and 28°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 42% of years.

Warmth for growing adds up to 4,759 growing degree days a year (base 50°F), more than at 96% of the 113 Kentucky stations. 38% of them (1,812) have built up by the end of June, and July adds the most, 927. Precipitation totals 48.4 inches a year, most in May (5.2") and least in January (3.4"); May to September bring 43% of it.

The nearest other station, Louisville Mcalpine, KY, 10 miles northeast of Louisville, has the same 50% last-frost date, a first frost 2 days later (November 9), a season 3 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, 7.3 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 23 days after the last snow.

ZIP 40258 is 7 miles from Louisville International Airport, KY, which stands at 488 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 9 other ZIP codes share the station; its figures are presented in full for 40214 (Louisville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 40258 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.