Frost Dates for 95448 — Healdsburg, California

Half of springs at Healdsburg, CA see their last 32°F night by February 15; only one in ten is past it by January 4, and one in ten still has one after March 17. Planting tender crops after February 28 leaves a 30% risk of a frost on them, after March 6 20%, and after March 17 10%. The 30 days between the even-odds date and the one-in-ten date is narrower than at 48% 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 December 2 in half of years, as early as November 14 one year in ten, and holds off past January 1 one year in ten. A hard freeze of 28°F follows 15 days later, around December 17; in spring the one-in-ten date for 28°F is February 2, 43 days before the 32°F one. The freeze-free season lasts 292 days in a typical year, longer than at 59% of the 219 California stations; it reaches 334 days one year in ten and falls short of 254 one year in ten. On average 13 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 42 days longer, to about March 29, and return around November 16. A 24°F night is unusual: 22% of winters had one.

July is the warmest month at Healdsburg, CA, averaging 89°F by day and 54°F at night; December is the coldest at 57°F and 39°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 56% of years and March still brings one in 24% of years.

Warmth for growing adds up to 3,988 growing degree days a year (base 50°F), fewer than at 60% of the 283 California stations. 39% of them (1,555) have built up by the end of June, and July adds the most, 667. Precipitation totals 42.9 inches a year, most in December (8.5") and least in July (0.0"); May to September bring 5% of it.

The nearest other station, Santa Rosa Sonoma Co Airport, CA, 8 miles southeast of Healdsburg, has a last frost 15 days later (March 2), a first frost 12 days earlier (November 20), a season 30 days shorter.

Measurable snow is rare here: only 1 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Healdsburg, CA, 1.2 miles away, so there is no typical first-snow date to plan around.

ZIP 95448 is 1 mile from Healdsburg, CA, which stands at 177 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 95448 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.