Frost Dates for 98237 — Concrete, Washington

Half of springs at Concrete Ppl Fish Stn, WA see their last 32°F night by March 28; only one in ten is past it by March 7, and one in ten still has one after April 19. Planting tender crops after April 5 leaves a 30% risk of a frost on them, after April 10 20%, and after April 19 10%. The 22 days between the even-odds date and the one-in-ten date is wider than at 71% 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 14 in half of years, as early as October 23 one year in ten, and holds off past December 4 one year in ten. A hard freeze of 28°F follows 18 days later, around December 2; in spring the one-in-ten date for 28°F is March 20, 30 days before the 32°F one. The freeze-free season lasts 229 days in a typical year, longer than at 81% of the 113 Washington stations; it reaches 260 days one year in ten and falls short of 201 one year in ten. On average 47 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 28 days longer, to about April 25, and return around October 25. Nights of 24°F, cold enough to damage hardier plants, come in 86% of winters and 16°F in 19%.

August is the warmest month at Concrete Ppl Fish Stn, WA, averaging 77°F by day and 54°F at night; December is the coldest at 42°F and 34°F. A freezing night is all but certain in every month from December to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 40% of years.

Warmth for growing adds up to 1,850 growing degree days a year (base 50°F), fewer than at 62% of the 113 Washington stations. 28% of them (525) have built up by the end of June, and August adds the most, 470. Precipitation totals 71.2 inches a year, most in November (11.5") and least in July (1.2"); May to September bring 17% of it.

The nearest other station, Darrington Rs, WA, 17 miles south of Concrete and 355 feet higher, has a last frost 19 days later (April 16), a first frost 22 days earlier (October 23), a season 39 days shorter.

The first measurable snow (0.1 inch or more) in Concrete usually arrives around December 14, and the last of the season around February 14. Those are the middle dates across the winters of 1991–2020 at Concrete Ppl Fish Stn, WA, 3.5 miles away: half of years saw snow earlier, half later. Snow fell in 95% of those winters. The last 32°F night of spring typically comes 42 days after the last snow.

ZIP 98237 is 4 miles from Concrete Ppl Fish Stn, WA, which stands at 195 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 98237 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.