Frost Dates for 66538 — Seneca, Kansas

Half of springs at Baileyville, KS see their last 32°F night by April 22; only one in ten is past it by April 10, and one in ten still has one after May 2. Planting tender crops after April 26 leaves a 30% risk of a frost on them, after April 29 20%, and after May 2 10%. The 10 days between the even-odds date and the one-in-ten date is the narrowest of the 110 Kansas stations behind this site's ZIP pages, so the end of frost is fairly predictable.

In fall the first 32°F night comes by October 13 in half of years, as early as September 27 one year in ten, and holds off past October 25 one year in ten. A hard freeze of 28°F follows 10 days later, around October 23; in spring the one-in-ten date for 28°F is April 25, 7 days before the 32°F one. The freeze-free season lasts 173 days in a typical year, shorter than at 85% of the 110 Kansas stations; it reaches 190 days one year in ten and falls short of 155 one year in ten. On average 139 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 8 days longer, to about April 30, and return around October 3. Severe cold of 16°F or below comes every winter, usually between November 19 and March 17.

July is the warmest month at Baileyville, KS, averaging 87°F by day and 65°F at night; January is the coldest at 35°F and 15°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 15% of years.

Warmth for growing adds up to 3,476 growing degree days a year (base 50°F), fewer than at 95% of the 110 Kansas stations. 36% of them (1,249) have built up by the end of June, and July adds the most, 793. Precipitation totals 30.6 inches a year, most in May (4.4") and least in January (0.6"); May to September bring 59% of it.

The nearest other station, Hiawatha 1 S, KS, 27 miles east of Seneca and 235 feet lower, has a last frost 8 days earlier (April 14), a first frost 9 days later (October 22), a season 15 days longer.

The first measurable snow (0.1 inch or more) in Seneca usually arrives around November 24, and the last of the season around March 25. Those are the middle dates across the winters of 1991–2020 at Centralia, KS, 9 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 28 days after the last snow.

ZIP 66538 is 7 miles from Baileyville, KS, which stands at 1,296 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 66538 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.