Frost Dates for 95688 — Vacaville, California

Half of springs at Vacaville Nut Tree Airport, CA see their last 32°F night by February 18; only one in ten is past it by January 11, and one in ten still has one after March 25. Planting tender crops after March 3 leaves a 30% risk of a frost on them, after March 10 20%, and after March 25 10%. The 35 days between the even-odds date and the one-in-ten date is wider than at 71% 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 28 in half of years, as early as November 12 one year in ten, and holds off past December 18 one year in ten. A hard freeze of 28°F follows 12 days later, around December 10; in spring the one-in-ten date for 28°F is February 17, 36 days before the 32°F one. The freeze-free season lasts 283 days in a typical year, longer than at 54% of the 219 California stations; it reaches 325 days one year in ten and falls short of 245 one year in ten. On average 21 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 38 days longer, to about March 28, and return around November 13. A 24°F night is unusual: 43% of winters had one.

July is the warmest month at Vacaville Nut Tree Airport, CA, averaging 95°F by day and 59°F at night; December is the coldest at 58°F and 37°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 59% of years and March still brings one in 29% of years.

Warmth for growing adds up to 4,707 growing degree days a year (base 50°F), more than at 55% of the 283 California stations. 37% of them (1,753) have built up by the end of June, and July adds the most, 837. Precipitation totals 25.0 inches a year, most in January (5.3") and least in July (0.0"); May to September bring 4% of it.

The nearest other station, Fairfield, CA, 8 miles southwest of Vacaville, has a last frost 34 days earlier (January 15), a first frost 16 days later (December 14), a season 53 days longer.

Measurable snow is rare here: only 0 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at Vacaville, CA, 2 miles away, so there is no typical first-snow date to plan around.

ZIP 95688 is 2 miles from Vacaville Nut Tree Airport, CA, which stands at 109 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 95687 (Vacaville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 95688 in zone 9b, the band where the coldest night of the year averaged 25 to 30°F (-3.9 to -1.1°C) over 1991–2020; a zone describes winter lows, not frost dates.