Frost Dates for 98229 — Bellingham, Washington

Half of springs at Bellingham 3 SSW, WA see their last 32°F night by April 1; only one in ten is past it by March 11, and one in ten still has one after April 24. Planting tender crops after April 8 leaves a 30% risk of a frost on them, after April 14 20%, and after April 24 10%. The 23 days between the even-odds date and the one-in-ten date is wider than at 81% 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 15 one year in ten, and holds off past November 23 one year in ten. A hard freeze of 28°F follows 19 days later, around November 21; 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 216 days in a typical year, longer than at 70% of the 113 Washington stations; it reaches 243 days one year in ten and falls short of 188 one year in ten. On average 43 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 26 days longer, to about April 27, and return around October 18. Nights of 24°F, cold enough to damage hardier plants, come in 98% of winters and 16°F in 42%.

July is the warmest month at Bellingham 3 SSW, WA, averaging 75°F by day and 54°F at night; December is the coldest at 47°F and 35°F. A freezing night is all but certain in every month from November 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 47% of years.

Warmth for growing adds up to 1,880 growing degree days a year (base 50°F), fewer than at 59% of the 113 Washington stations. 31% of them (585) have built up by the end of June, and July adds the most, 445. Precipitation totals 36.1 inches a year, most in November (5.7") and least in July (1.0"); May to September bring 22% of it.

The nearest other station, Bellingham International Airport, WA, 7 miles northwest of Bellingham, has a last frost 1 day earlier (March 31), a first frost 3 days earlier (October 30), a season 5 days shorter.

The first measurable snow (0.1 inch or more) in Bellingham usually arrives around December 23, and the last of the season around January 23. Those are the middle dates across the winters of 1991–2020 at Bellingham 3 SSW, WA, 3.5 miles away: half of years saw snow earlier, half later. Snow fell in 74% of those winters. The last 32°F night of spring typically comes 68 days after the last snow.

ZIP 98229 is 4 miles from Bellingham 3 SSW, WA, which stands at 15 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 98225 (Bellingham). The 2023 USDA Plant Hardiness Zone Map lists ZIP 98229 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.