Frost Dates for 66066 — Oskaloosa, Kansas

Half of springs at Oskaloosa 4 NE, KS see their last 32°F night by April 16; only one in ten is past it by April 2, and one in ten still has one after April 29. Planting tender crops after April 21 leaves a 30% risk of a frost on them, after April 24 20%, and after April 29 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 65% of the 110 Kansas stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 22 in half of years, as early as October 5 one year in ten, and holds off past November 4 one year in ten. A hard freeze of 28°F follows 10 days later, around November 1; in spring the one-in-ten date for 28°F is April 21, 8 days before the 32°F one. The freeze-free season lasts 188 days in a typical year, shorter than at 48% of the 110 Kansas stations; it reaches 208 days one year in ten and falls short of 169 one year in ten. On average 113 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 9 days longer, to about April 25, and return around October 11. Severe cold of 16°F or below comes every winter, usually between November 28 and March 8.

July is the warmest month at Oskaloosa 4 NE, KS, averaging 90°F by day and 68°F at night; January is the coldest at 38°F and 18°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month.

Warmth for growing adds up to 4,043 growing degree days a year (base 50°F), fewer than at 60% of the 110 Kansas stations. 36% of them (1,460) have built up by the end of June, and July adds the most, 899. Precipitation totals 38.4 inches a year, most in June (5.4") and least in January (1.0"); May to September bring 61% of it.

The nearest other station, Perry Lake, KS, 8 miles southwest of Oskaloosa and 152 feet lower, has a last frost 3 days earlier (April 13), a first frost 2 days later (October 24), a season 3 days longer.

The first measurable snow (0.1 inch or more) in Oskaloosa usually arrives around December 8, and the last of the season around February 27. Those are the middle dates across the winters of 1991–2020 at Oskaloosa 4 NE, KS, 3.4 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 48 days after the last snow.

ZIP 66066 is 3 miles from Oskaloosa 4 NE, KS, which stands at 1,109 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 66066 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.