Frost Dates for 94553 — Martinez, California

Half of springs at Martinez Wtp, CA see their last 32°F night by February 28; only one in ten is past it by January 29, and one in ten still has one after April 5. Planting tender crops after March 11 leaves a 30% risk of a frost on them, after March 22 20%, and after April 5 10%. The 36 days between the even-odds date and the one-in-ten date is wider than at 75% 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 22 in half of years, as early as November 7 one year in ten, and holds off past December 10 one year in ten. A hard freeze of 28°F follows 17 days later, around December 9; in spring the one-in-ten date for 28°F is February 25, 39 days before the 32°F one. The freeze-free season lasts 266 days in a typical year, shorter than at 59% of the 219 California stations; it reaches 302 days one year in ten and falls short of 226 one year in ten. On average 16 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 10, and return around November 7. Nights of 24°F, cold enough to damage hardier plants, come in 50% of winters.

July is the warmest month at Martinez Wtp, CA, averaging 88°F by day and 51°F at night; January is the coldest at 56°F and 35°F. A freezing night is all but certain in every month from December to January (a 90% chance or more). From May to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 77% of years and March still brings one in 39% of years and April still brings one in 13% of years.

Warmth for growing adds up to 3,421 growing degree days a year (base 50°F), fewer than at 74% of the 283 California stations. 37% of them (1,268) have built up by the end of June, and July adds the most, 614. Precipitation totals 19.4 inches a year, most in January (3.9") and least in July (0.0"); May to September bring 5% of it.

The nearest other station, Concord Wwtp, CA, 3 miles southeast of Martinez, has a last frost 52 days earlier (January 7), a first frost 27 days later (December 19), a season 80 days longer.

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Martinez Wtp, CA, 1 miles away, so there is no typical first-snow date to plan around.

ZIP 94553 is 1 mile from Martinez Wtp, CA, which stands at 40 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 94553 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.