Frost Dates for 95492 — Windsor, California

Half of springs at Santa Rosa Sonoma Co Airport, CA see their last 32°F night by March 2; only one in ten is past it by January 27, and one in ten still has one after April 2. Planting tender crops after March 14 leaves a 30% risk of a frost on them, after March 24 20%, and after April 2 10%. The 31 days between the even-odds date and the one-in-ten date is wider than at 53% 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 20 in half of years, as early as November 1 one year in ten, and holds off past December 10 one year in ten. A hard freeze of 28°F follows 15 days later, around December 5; in spring the one-in-ten date for 28°F is February 23, 38 days before the 32°F one. The freeze-free season lasts 262 days in a typical year, shorter than at 61% of the 219 California stations; it reaches 307 days one year in ten and falls short of 223 one year in ten. On average 31 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 41 days longer, to about April 12, and return around November 3. A 24°F night is unusual: 45% of winters had one.

August is the warmest month at Santa Rosa Sonoma Co Airport, CA, averaging 84°F by day and 52°F at night; December is the coldest at 58°F and 37°F. From May to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 71% of years and March still brings one in 48% of years and April still brings one in 11% of years.

Warmth for growing adds up to 3,302 growing degree days a year (base 50°F), fewer than at 77% of the 283 California stations. 37% of them (1,213) have built up by the end of June, and August adds the most, 558. Precipitation totals 34.0 inches a year, most in December (6.8") and least in July (0.0"); May to September bring 5% of it.

The nearest other station, Healdsburg, CA, 7 miles northwest of Windsor, has a last frost 15 days earlier (February 15), a first frost 12 days later (December 2), a season 30 days longer.

Measurable snow is rare here: only 1 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Healdsburg, CA, 6.6 miles away, so there is no typical first-snow date to plan around.

ZIP 95492 is 3 miles from Santa Rosa Sonoma Co Airport, CA, which stands at 114 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 95492 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.