Frost Dates for 95470 — Redwood Valley, California

Half of springs at Potter Valley Powerhouse, CA see their last 32°F night by April 8; only one in ten is past it by March 11, and one in ten still has one after April 29. Planting tender crops after April 17 leaves a 30% risk of a frost on them, after April 22 20%, and after April 29 10%. The 21 days between the even-odds date and the one-in-ten date is narrower than at 84% 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 November 6 in half of years, as early as October 20 one year in ten, and holds off past November 24 one year in ten. A hard freeze of 28°F follows 16 days later, around November 22; in spring the one-in-ten date for 28°F is April 2, 27 days before the 32°F one. The freeze-free season lasts 211 days in a typical year, shorter than at 78% of the 219 California stations; it reaches 243 days one year in ten and falls short of 184 one year in ten. On average 54 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 24 days longer, to about May 2, and return around October 21. Nights of 24°F, cold enough to damage hardier plants, come in 90% of winters and 16°F in 9%.

July is the warmest month at Potter Valley Powerhouse, CA, averaging 95°F by day and 54°F at night; December is the coldest at 56°F and 35°F. A freezing night is all but certain in every month from November 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 87% of years and April still brings one in 62% of years.

Warmth for growing adds up to 3,836 growing degree days a year (base 50°F), fewer than at 66% of the 283 California stations. 34% of them (1,306) have built up by the end of June, and July adds the most, 766. Precipitation totals 45.1 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, Ukiah, CA, 10 miles south of Redwood Valley and 382 feet lower, has a last frost 20 days earlier (March 19), a first frost 14 days later (November 20), a season 34 days longer.

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Potter Valley Powerhouse, CA, 7.2 miles away, so there is no typical first-snow date to plan around.

ZIP 95470 is 7 miles from Potter Valley Powerhouse, CA, which stands at 1,018 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 95470 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.