Frost Dates for 67356 — Oswego, Kansas

Half of springs at Parsons 2 NW, KS see their last 32°F night by April 11; only one in ten is past it by March 27, and one in ten still has one after April 26. Planting tender crops after April 18 leaves a 30% risk of a frost on them, after April 22 20%, and after April 26 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 57% of the 110 Kansas stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 26 in half of years, as early as October 13 one year in ten, and holds off past November 6 one year in ten. A hard freeze of 28°F follows 7 days later, around November 2; in spring the one-in-ten date for 28°F is April 18, 8 days before the 32°F one. The freeze-free season lasts 196 days in a typical year, longer than at 74% of the 110 Kansas stations; it reaches 217 days one year in ten and falls short of 175 one year in ten. On average 104 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 22, and return around October 17. Severe cold of 16°F or below comes every winter, usually between December 6 and February 27.

July is the warmest month at Parsons 2 NW, KS, averaging 90°F by day and 69°F at night; January is the coldest at 43°F and 22°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 81% of years.

Warmth for growing adds up to 4,288 growing degree days a year (base 50°F), more than at 73% of the 110 Kansas stations. 36% of them (1,546) have built up by the end of June, and July adds the most, 911. Precipitation totals 44.8 inches a year, most in May (6.8") and least in January (1.4"); May to September bring 57% of it.

The nearest other station, Columbus, KS, 16 miles east of Oswego, has a last frost 6 days earlier (April 5), a first frost 5 days later (October 31), a season 12 days longer.

The first measurable snow (0.1 inch or more) in Oswego usually arrives around December 9, and the last of the season around February 26. Those are the middle dates across the winters of 1991–2020 at Bartlett, KS, 10.2 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 44 days after the last snow.

ZIP 67356 is 15 miles from Parsons 2 NW, KS, which stands at 910 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 67357 (Parsons). The 2023 USDA Plant Hardiness Zone Map lists ZIP 67356 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.