Frost Dates for 98831 — Manson, Washington

Half of springs at Chelan, WA see their last 32°F night by April 17; only one in ten is past it by April 3, and one in ten still has one after April 30. Planting tender crops after April 24 leaves a 30% risk of a frost on them, after April 27 20%, and after April 30 10%. The 13 days between the even-odds date and the one-in-ten date is the narrowest of the 113 Washington 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 9 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 13 days later, around November 4; in spring the one-in-ten date for 28°F is April 15, 15 days before the 32°F one. The freeze-free season lasts 187 days in a typical year, shorter than at 53% of the 113 Washington stations; it reaches 206 days one year in ten and falls short of 170 one year in ten. On average 109 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 14 days longer, to about May 1, and return around October 10. Severe cold of 16°F or below comes in 99% of winters, usually between December 10 and February 14.

July is the warmest month at Chelan, WA, averaging 87°F by day and 59°F at night; January is the coldest at 34°F and 22°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 2,710 growing degree days a year (base 50°F), more than at 81% of the 113 Washington stations. 30% of them (817) have built up by the end of June, and July adds the most, 708. Precipitation totals 11.9 inches a year, most in December (1.8") and least in August (0.3"); May to September bring 25% of it.

The nearest other station, Entiat Fish Hatchery, WA, 17 miles southwest of Manson and 167 feet lower, has a last frost 12 days earlier (April 5), a first frost 2 days later (October 24), a season 13 days longer.

The first measurable snow (0.1 inch or more) in Manson usually arrives around November 29, and the last of the season around February 25. Those are the middle dates across the winters of 1991–2020 at Chelan, WA, 8.2 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 51 days after the last snow.

ZIP 98831 is 8 miles from Chelan, WA, which stands at 1,194 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 98816 (Chelan). The 2023 USDA Plant Hardiness Zone Map lists ZIP 98831 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.