Frost Dates for 66040 — La Cygne, Kansas

Half of springs at Mound City, KS see their last 32°F night by April 13; only one in ten is past it by March 29, and one in ten still has one after May 1. Planting tender crops after April 21 leaves a 30% risk of a frost on them, after April 25 20%, and after May 1 10%. The 18 days between the even-odds date and the one-in-ten date is the widest of the 110 Kansas stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 23 in half of years, as early as October 8 one year in ten, and holds off past November 4 one year in ten. A hard freeze of 28°F follows 9 days later, around November 1; in spring the one-in-ten date for 28°F is April 18, 13 days before the 32°F one. The freeze-free season lasts 192 days in a typical year, longer than at 65% of the 110 Kansas stations; it reaches 215 days one year in ten and falls short of 170 one year in ten. On average 118 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 25, and return around October 13. Severe cold of 16°F or below comes every winter, usually between December 2 and March 2.

July is the warmest month at Mound City, KS, averaging 89°F by day and 69°F at night; January is the coldest at 41°F and 20°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 82% of years and May still brings one in 10% of years.

Warmth for growing adds up to 4,013 growing degree days a year (base 50°F), fewer than at 65% of the 110 Kansas stations. 36% of them (1,439) have built up by the end of June, and July adds the most, 887. Precipitation totals 41.4 inches a year, most in May (5.3") and least in January (1.3"); May to September bring 55% of it.

The nearest other station, Mound City 1SSW, KS, 16 miles south of La Cygne, has a last frost 2 days later (April 15), a first frost 1 day earlier (October 22), a season 4 days shorter.

The first measurable snow (0.1 inch or more) in La Cygne usually arrives around December 19, and the last of the season around February 19. Those are the middle dates across the winters of 1991–2020 at Mound City, KS, 15.1 miles away: half of years saw snow earlier, half later. Snow fell in 89% of those winters. The last 32°F night of spring typically comes 53 days after the last snow.

ZIP 66040 is 15 miles from Mound City, KS, which stands at 840 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 66040 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.