Frost Dates for 98370 — Poulsbo, Washington

Half of springs at Bremerton, WA see their last 32°F night by March 29; only one in ten is past it by March 5, and one in ten still has one after April 24. Planting tender crops after April 7 leaves a 30% risk of a frost on them, after April 15 20%, and after April 24 10%. The 26 days between the even-odds date and the one-in-ten date is wider than at 89% 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 26 one year in ten, and holds off past December 1 one year in ten. A hard freeze of 28°F follows 16 days later, around November 30; in spring the one-in-ten date for 28°F is March 27, 28 days before the 32°F one. The freeze-free season lasts 227 days in a typical year, longer than at 80% of the 113 Washington stations; it reaches 257 days one year in ten and falls short of 197 one year in ten. On average 42 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 27 days longer, to about April 25, and return around October 27. Nights of 24°F, cold enough to damage hardier plants, come in 87% of winters and 16°F in 5%.

August is the warmest month at Bremerton, WA, averaging 77°F by day and 55°F at night; December is the coldest at 46°F and 35°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 88% of years and April still brings one in 40% of years.

Warmth for growing adds up to 2,058 growing degree days a year (base 50°F), more than at 56% of the 113 Washington stations. 29% of them (603) have built up by the end of June, and August adds the most, 502. Precipitation totals 56.9 inches a year, most in December (9.9") and least in July (0.8"); May to September bring 14% of it.

The nearest other station, Quilcene 2 SW, WA, 14 miles west of Poulsbo, has a last frost 13 days later (April 11), a first frost 17 days earlier (October 28), a season 28 days shorter.

The first measurable snow (0.1 inch or more) in Poulsbo usually arrives around January 12, and the last of the season around January 24. Those are the middle dates across the winters of 1991–2020 at Bremerton, WA, 12.3 miles away: half of years saw snow earlier, half later. Snow fell in 61% of those winters. The last 32°F night of spring typically comes 64 days after the last snow.

ZIP 98370 is 12 miles from Bremerton, WA, which stands at 110 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 13 other ZIP codes share the station; its figures are presented in full for 98366 (Port Orchard). The 2023 USDA Plant Hardiness Zone Map lists ZIP 98370 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.