Frost Dates for 66861 — Marion, Kansas

Half of springs at Marion Rsvr, KS see their last 32°F night by April 8; only one in ten is past it by March 23, and one in ten still has one after April 25. Planting tender crops after April 16 leaves a 30% risk of a frost on them, after April 20 20%, and after April 25 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 85% of the 110 Kansas stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 30 in half of years, as early as October 17 one year in ten, and holds off past November 12 one year in ten. A hard freeze of 28°F follows 7 days later, around November 6; in spring the one-in-ten date for 28°F is April 17, 8 days before the 32°F one. The freeze-free season lasts 202 days in a typical year, longer than at 88% of the 110 Kansas stations; it reaches 224 days one year in ten and falls short of 183 one year in ten. On average 119 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 19, and return around October 21. Severe cold of 16°F or below comes every winter, usually between December 7 and February 28.

July is the warmest month at Marion Rsvr, KS, averaging 92°F by day and 70°F at night; January is the coldest at 41°F and 21°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 74% of years.

Warmth for growing adds up to 4,479 growing degree days a year (base 50°F), more than at 90% of the 110 Kansas stations. 36% of them (1,605) have built up by the end of June, and July adds the most, 966. Precipitation totals 34.0 inches a year, most in May (5.2") and least in January (0.8"); May to September bring 63% of it.

The nearest other station, Herington, KS, 21 miles north of Marion, has a last frost 16 days later (April 24), a first frost 16 days earlier (October 14), a season 29 days shorter.

The first measurable snow (0.1 inch or more) in Marion usually arrives around December 8, and the last of the season around March 7. Those are the middle dates across the winters of 1991–2020 at Hillsboro, KS, 10 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 32 days after the last snow.

ZIP 66861 is 3 miles from Marion Rsvr, KS, which stands at 1,369 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 67063 (Hillsboro). The 2023 USDA Plant Hardiness Zone Map lists ZIP 66861 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.