Frost Dates for 99114 — Colville, Washington

Half of springs at Colville, WA see their last 32°F night by May 2; only one in ten is past it by April 19, and one in ten still has one after May 17. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 12 20%, and after May 17 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 81% of the 113 Washington stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 2 in half of years, as early as September 19 one year in ten, and holds off past October 17 one year in ten. A hard freeze of 28°F follows 12 days later, around October 14; in spring the one-in-ten date for 28°F is May 2, 15 days before the 32°F one. The freeze-free season lasts 153 days in a typical year, shorter than at 84% of the 113 Washington stations; it reaches 175 days one year in ten and falls short of 132 one year in ten. On average 144 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 15 days longer, to about May 17, and return around September 22. Severe cold of 16°F or below comes every winter, usually between November 25 and February 26.

July is the warmest month at Colville, WA, averaging 88°F by day and 53°F at night; January is the coldest at 34°F and 23°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 57% of years.

Warmth for growing adds up to 2,357 growing degree days a year (base 50°F), more than at 67% of the 113 Washington stations. 30% of them (715) have built up by the end of June, and July adds the most, 635. Precipitation totals 19.8 inches a year, most in December (2.8") and least in August (0.7"); May to September bring 31% of it.

The nearest other station, Chewelah, WA, 27 miles south of Colville, has a last frost 14 days later (May 16), a first frost 17 days earlier (September 15), a season 33 days shorter.

The first measurable snow (0.1 inch or more) in Colville usually arrives around November 16, and the last of the season around March 12. Those are the middle dates across the winters of 1991–2020 at Colville, WA, 9.9 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 51 days after the last snow.

ZIP 99114 is 10 miles from Colville, WA, which stands at 1,554 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 99114 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.