Frost Dates for 98610 — Carson, Washington

Half of springs at Carson Fish Hatchery, WA see their last 32°F night by May 2; only one in ten is past it by April 15, and one in ten still has one after May 20. Planting tender crops after May 9 leaves a 30% risk of a frost on them, after May 13 20%, and after May 20 10%. The 18 days between the even-odds date and the one-in-ten date is narrower than at 56% of the 113 Washington stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 9 in half of years, as early as September 22 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 21 days later, around October 30; in spring the one-in-ten date for 28°F is May 1, 19 days before the 32°F one. The freeze-free season lasts 161 days in a typical year, shorter than at 79% of the 113 Washington stations; it reaches 188 days one year in ten and falls short of 136 one year in ten. On average 126 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 19 days longer, to about May 21, and return around September 24. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 75%.

August is the warmest month at Carson Fish Hatchery, WA, averaging 82°F by day and 49°F at night; December is the coldest at 38°F and 29°F. A freezing night is all but certain in every month from November 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 56% of years.

Warmth for growing adds up to 1,725 growing degree days a year (base 50°F), fewer than at 74% of the 113 Washington stations. 26% of them (450) have built up by the end of June, and August adds the most, 476. Precipitation totals 89.0 inches a year, most in December (15.8") and least in July (0.5"); May to September bring 11% of it.

The nearest other station, Cascade Locks, OR, 9 miles south of Carson and 992 feet lower, has a last frost 39 days earlier (March 24), a first frost 42 days later (November 20), a season 81 days longer.

The first measurable snow (0.1 inch or more) in Carson usually arrives around November 27, and the last of the season around March 10. Those are the middle dates across the winters of 1991–2020 at Carson Fish Hatchery, WA, 5.5 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 53 days after the last snow.

ZIP 98610 is 6 miles from Carson Fish Hatchery, WA, which stands at 1,134 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 98610 in zone 8a, the band where the coldest night of the year averaged 10 to 15°F (-12.2 to -9.4°C) over 1991–2020; a zone describes winter lows, not frost dates.