Frost Dates for 95129 — San Jose, California

In the 76% of winters that bring a 32°F night, half of springs at San Jose, CA see their last 32°F night by January 12; only one in ten is past it by December 20, and one in ten still has one after February 14. Counting the winters with no freeze at all, the risk of a 32°F night after February 14 is under 8% and after January 12 38%. The 33 days between the even-odds date and the one-in-ten date is wider than at 61% 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 22 in half of years, as early as December 1 one year in ten, and holds off past January 20 one year in ten. A hard freeze of 28°F is less common: it came in 20% of winters. The freeze-free season lasts 347 days in a typical year, longer than at 92% of the 219 California stations; it reaches 365 days one year in ten and falls short of 313 one year in ten. On average 3 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 31 days longer, to about February 12, and return around December 3. A 24°F night is unusual: 1% of winters had one.

August is the warmest month at San Jose, CA, averaging 81°F by day and 59°F at night; December is the coldest at 60°F and 42°F. From March to November the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 17% of years.

Warmth for growing adds up to 4,040 growing degree days a year (base 50°F), fewer than at 58% of the 283 California stations. 39% of them (1,556) have built up by the end of June, and August adds the most, 620. Precipitation totals 13.6 inches a year, most in January (2.8") and least in July (0.0"); May to September bring 6% of it.

The nearest other station, Los Gatos, CA, 6 miles southeast of San Jose and 314 feet higher, has a last frost 21 days later (February 2), a first frost 16 days earlier (December 6), a season 37 days shorter.

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Los Gatos, CA, 5.7 miles away, so there is no typical first-snow date to plan around.

ZIP 95129 is 6 miles from San Jose, CA, which stands at 51 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 95035 (Milpitas). The 2023 USDA Plant Hardiness Zone Map lists ZIP 95129 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.