Frost Dates for 98642 — Ridgefield, Washington

Half of springs at Scappoose Ind Airport, OR see their last 32°F night by April 10; only one in ten is past it by March 17, and one in ten still has one after May 1. Planting tender crops after April 19 leaves a 30% risk of a frost on them, after April 25 20%, and after May 1 10%. The 21 days between the even-odds date and the one-in-ten date is wider than at 65% of the 113 Washington stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by November 2 in half of years, as early as October 16 one year in ten, and holds off past November 23 one year in ten. A hard freeze of 28°F follows 17 days later, around November 19; in spring the one-in-ten date for 28°F is March 28, 34 days before the 32°F one. The freeze-free season lasts 209 days in a typical year, longer than at 65% of the 113 Washington stations; it reaches 238 days one year in ten and falls short of 182 one year in ten. On average 61 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 20 days longer, to about April 30, and return around October 16. Nights of 24°F, cold enough to damage hardier plants, come in 95% of winters and 16°F in 27%.

August is the warmest month at Scappoose Ind Airport, OR, averaging 82°F by day and 54°F at night; December is the coldest at 46°F and 34°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 62% of years and May still brings one in 11% of years.

Warmth for growing adds up to 2,345 growing degree days a year (base 50°F), more than at 66% of the 113 Washington stations. 29% of them (687) have built up by the end of June, and August adds the most, 564. Precipitation totals 42.4 inches a year, most in December (7.3") and least in July (0.5"); May to September bring 15% of it.

The nearest other station, Battle Ground, WA, 8 miles east of Ridgefield and 229 feet higher, has a last frost 16 days later (April 26), a first frost 17 days earlier (October 16), a season 35 days shorter.

Measurable snow is rare here: only 11 of 27 winters from 1991 to 2020 recorded 0.1 inch or more at Vancouver 4 NNE, WA, 8.5 miles away, so there is no typical first-snow date to plan around.

ZIP 98642 is 8 miles from Scappoose Ind Airport, OR, which stands at 55 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 98642 in zone 8b, the band where the coldest night of the year averaged 15 to 20°F (-9.4 to -6.7°C) over 1991–2020; a zone describes winter lows, not frost dates.