Frost Dates for 40229 — Louisville, Kentucky

Half of springs at Louisville WFO, KY see their last 32°F night by April 6; only one in ten is past it by March 23, and one in ten still has one after April 23. Planting tender crops after April 13 leaves a 30% risk of a frost on them, after April 17 20%, and after April 23 10%. The 17 days between the even-odds date and the one-in-ten date is narrower than at 47% of the 113 Kentucky stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 1 in half of years, as early as October 21 one year in ten, and holds off past November 15 one year in ten. A hard freeze of 28°F follows 10 days later, around November 11; in spring the one-in-ten date for 28°F is April 9, 14 days before the 32°F one. The freeze-free season lasts 209 days in a typical year, longer than at 86% of the 113 Kentucky stations; it reaches 229 days one year in ten and falls short of 187 one year in ten. On average 85 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 19, and return around October 23. Severe cold of 16°F or below comes every winter, usually between December 19 and February 16.

July is the warmest month at Louisville WFO, KY, averaging 87°F by day and 68°F at night; January is the coldest at 42°F and 26°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 67% of years.

Warmth for growing adds up to 4,292 growing degree days a year (base 50°F), more than at 73% of the 113 Kentucky stations. 38% of them (1,617) have built up by the end of June, and July adds the most, 854. Precipitation totals 53.1 inches a year, most in May (5.8") and least in August (3.3"); May to September bring 42% of it.

The nearest other station, Louisville International Airport, KY, 8 miles northwest of Louisville, has a last frost 6 days earlier (March 31), a first frost 6 days later (November 7), a season 13 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 13. Those are the middle dates across the winters of 1991–2020 at Louisville WFO, KY, 2.5 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 24 days after the last snow.

ZIP 40229 is 3 miles from Louisville WFO, KY, which stands at 632 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 40291 (Louisville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 40229 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.