Frost Dates for 42406 — ZIP 42406

Half of springs at Henderson 8 SSW, KY see their last 32°F night by April 4; only one in ten is past it by March 22, and one in ten still has one after April 19. Planting tender crops after April 10 leaves a 30% risk of a frost on them, after April 14 20%, and after April 19 10%. The 15 days between the even-odds date and the one-in-ten date measure how much the end of the frost season moves from year to year.

In fall the first 32°F night comes by October 29 in half of years, as early as October 17 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 8; in spring the one-in-ten date for 28°F is April 10, 9 days before the 32°F one. The freeze-free season lasts 207 days in a typical year; it reaches 226 days one year in ten and falls short of 187 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 12 days longer, to about April 16, and return around October 20. Severe cold of 16°F or below comes every winter, usually between December 12 and February 22.

July is the warmest month at Henderson 8 SSW, 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 64% of years.

Warmth for growing adds up to 4,350 growing degree days a year (base 50°F). 38% of them (1,666) have built up by the end of June, and July adds the most, 860. Precipitation totals 46.3 inches a year, most in April (4.9") and least in August (2.9"); May to September bring 42% of it.

The nearest other station, Henderson State Police, KY, 9 miles east of ZIP 42406, has a last frost 5 days later (April 9), a first frost 3 days earlier (October 26), a season 9 days shorter.

The first measurable snow (0.1 inch or more) in ZIP 42406 usually arrives around December 20, and the last of the season around February 23. Those are the middle dates across the winters of 1991–2020 at Henderson 8 SSW, KY, 4.8 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 40 days after the last snow.

ZIP 42406 is 5 miles from Henderson 8 SSW, KY, which stands at 449 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 42455 (Sebree). The 2023 USDA Plant Hardiness Zone Map lists ZIP 42406 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.