Frost Dates for 95490 — Willits, California

Half of springs at Willits 1 NE, CA see their last 32°F night by May 5; only one in ten is past it by April 11, and one in ten still has one after May 31. Planting tender crops after May 17 leaves a 30% risk of a frost on them, after May 23 20%, and after May 31 10%. The 26 days between the even-odds date and the one-in-ten date is narrower than at 67% of the 220 California 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 October 9 in half of years, as early as September 24 one year in ten, and holds off past October 31 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 April 23, 38 days before the 32°F one. The freeze-free season lasts 157 days in a typical year, shorter than at 91% of the 219 California stations; it reaches 187 days one year in ten and falls short of 128 one year in ten. On average 95 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 June 1, and return around September 20. Nights of 24°F, cold enough to damage hardier plants, come in 94% of winters and 16°F in 13%.

July is the warmest month at Willits 1 NE, CA, averaging 84°F by day and 48°F at night; December is the coldest at 53°F and 32°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 57% of years.

Warmth for growing adds up to 2,093 growing degree days a year (base 50°F), fewer than at 92% of the 283 California stations. 28% of them (587) have built up by the end of June, and July adds the most, 488. Precipitation totals 49.3 inches a year, most in December (9.8") and least in July (0.0"); May to September bring 6% of it.

The nearest other station, Potter Valley Powerhouse, CA, 14 miles southeast of Willits and 335 feet lower, has a last frost 27 days earlier (April 8), a first frost 28 days later (November 6), a season 54 days longer.

Measurable snow is rare here: only 1 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Willits 1 NE, CA, 2.8 miles away, so there is no typical first-snow date to plan around.

ZIP 95490 is 3 miles from Willits 1 NE, CA, which stands at 1,353 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 95490 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°C) over 1991–2020; a zone describes winter lows, not frost dates.