What does USDA hardiness zone 10a mean in California?

Zone 10a means an average annual extreme minimum winter temperature of 30 to 35 °F — the standard USDA measure of which perennials survive winter. 71 locations in California fall in this zone. It does not set planting dates; see the frost calendar below for that.

Where in California's zone 10a is the growing season longest?

Los Angeles runs the longest season on this page at about 364 days; Glendora is shortest at about 199 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.

When should I plant tomatoes in California's zone 10a?

Using San Bernardino's frost dates (this page's median-season location): start seeds indoors about Jan 1, then transplant outside about Feb 3 – Feb 10. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.

Does every location in California's zone 10a have the same frost dates?

No — they do not all share a weather station, so frost dates vary by a week or more across the 71 locations listed (see the table above for each location's own dates).

USDA zone 10a in California

30 to 35 °F avg. annual extreme minimum · 71 locations in this group · NOAA 1991–2020 normals

USDA plant hardiness zone 10a covers 71 locations across California (average annual extreme minimum 30 to 35 °F): Anaheim, CA, Berkeley, CA, Bodega Bay, CA, Bolinas, CA, Borrego Springs, CA, Brawley, CA, and 65 more. Average last spring frost across this group ranges January 2 (Los Angeles) to April 29 (Pala), and growing seasons run 199–364 days (Glendora to Los Angeles) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every California location's own frost dates; the printable planting calendar uses San Bernardino, this group's median-season location.

USDA zone: 10a30 to 35 °F
Last frost range: Jan 2–Apr 29avg, 32°F
First frost range: Nov 8–Dec 30avg, 32°F
Growing season range: 199–364days

Locations in this group

Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.

Own frost dates per location.
Location	Also covers	Nearest station	Last frost	First frost	Season (days)
Anaheim	Chino Hills, Fullerton, Yorba Linda, Diamond Bar, Rowland Heights, Brea, +5 more	Anaheim	frost-free	frost-free	365
Berkeley	—	Berkeley	frost-free	frost-free	365
Bodega Bay	Dillon Beach, Sereno del Mar	Graton	Mar 20	Nov 13	240
Bolinas	Corte Madera, Kentfield, Larkspur, Fairfax, Stinson Beach	Kentfield	Jan 16	Dec 18	334
Borrego Springs	Salton	Ocotillo Wells 2w	frost-free	frost-free	365
Brawley	El Centro Naval Air Facility, Seeley	Imperial	Jan 4	Dec 26	360
Callender	Guadalupe, Casmalia	Santa Maria Public Ap	Feb 4	Dec 13	315
Cambria	San Simeon	Hearst Castle	frost-free	frost-free	365
Carlsbad	Encinitas	Carlsbad Palomar Ap	frost-free	frost-free	365
Carmel Valley	—	Big Sur Stn	Feb 13	Dec 27	323
Cayucos	—	Paso Robles	Mar 15	Nov 10	238
Daly	Broadmoor	San Francisco Oceanside	frost-free	frost-free	365
Desert Center	—	Eagle Mtn	frost-free	frost-free	365
Eastern Goleta Valley	Goleta, Mission Canyon	Santa Barbara Muni Ap	Jan 11	Dec 16	342
El Centro	Ocotillo, Heber, Holtville	El Centro 2 Ssw	Jan 3	Dec 27	363
El Rio	Saticoy	Oxnard Wfo	frost-free	frost-free	365
Escondido	—	San Pasqual Animal Pk	Feb 2	Dec 7	309
Fairbanks Ranch	—	San Diego Miramar Nas	frost-free	frost-free	365
Fremont	Newark	Newark	frost-free	frost-free	365
Glendale	Pasadena, Arcadia, Irwindale, La CaÃ±ada Flintridge, Alhambra, San Gabriel, +5 more	Pasadena	frost-free	frost-free	365
Glendora	Monrovia, Duarte, Sierra Madre	Mt Wilson Cbs	Apr 28	Nov 15	199
Half Moon Bay	El Granada, Montara	Half Moon Bay	Feb 6	Dec 17	328
Hasley Canyon	—	Sandberg	Apr 15	Nov 26	224
Hayward	San Leandro, San Lorenzo, Ashland	Hayward Air Terminal	frost-free	frost-free	365
Indio	—	Indio Fire Stn	frost-free	frost-free	365
Inverness	—	Bodega 6 Wsw	frost-free	frost-free	365
Irvine	Garden Grove, Tustin, Westminster, Stanton	Santa Ana Fire Stn	frost-free	frost-free	365
Jamul	—	San Diego Brown Fld	frost-free	frost-free	365
La Quinta	Indio, Coachella	Desert Resorts Rgnl Ap	Feb 7	Dec 2	298
Live Oak	—	Santa Cruz	Jan 29	Dec 13	323
Long Beach	Seal Beach, Buena Park, Lakewood, Cerritos, Cypress, Los Alamitos, +2 more	Long Beach Daugherty Fld	frost-free	frost-free	365
Los Angeles	—	Los Angeles Dwtn Usc Campus	frost-free	frost-free	365
Los Angeles	Simi Valley, Bell Canyon, Hidden Hills, Santa Susana	Woodland Hills Pierce College	Jan 24	Dec 15	329
Los Angeles	Santa Clarita, San Fernando, Santa Susana	Van Nuys Ap	frost-free	frost-free	365
Los Angeles	Glendale, Burbank, La Crescenta-Montrose, San Fernando	Burbank Valley Pump Plt	Jan 2	Dec 26	364
Los Olivos	Solvang	Cachuma Lake	Apr 11	Nov 8	209
Los Osos	Avila Beach, Pismo Beach, Grover Beach, California Polytechnic State University	San Luis Obispo Poly	Jan 16	Dec 25	349
Marina	—	Salinas #2	Feb 4	Dec 6	311
Mendocino	Little River	Ft Bragg 5 N	Mar 2	Dec 1	272
Moss Landing	—	Watsonville Wtr Wks	Jan 28	Dec 13	324
Oakland	San Leandro	Oakland Metro Intl Ap	Jan 7	Dec 23	356
Oakland	Berkeley, Piedmont, Emeryville	Oakland Museum	frost-free	frost-free	365
Oasis	Mecca	Mecca Fire Stn	Jan 6	Dec 22	352
Oceanside	Carlsbad, Camp Pendleton South	Oceanside Marina	frost-free	frost-free	365
Oceanside	Carlsbad, San Marcos, Vista, Fallbrook, Bonsall, Hidden Meadows	Vista	frost-free	frost-free	365
Ontario	Rancho Cucamonga, Chino, Pomona, Upland, Eastvale, Montclair	Chino Ap	Jan 17	Dec 19	335
Pacifica	San Mateo, Hillsborough, San Bruno, Millbrae, Brisbane	San Francisco Intl Ap	frost-free	frost-free	365
Pala	—	Palomar Mtn Obsy	Apr 29	Nov 18	201
Palm Springs	Desert Hot Springs, Palm Desert, Rancho Mirage, Thousand Palms, Indio Hills, Indian Wells	Palm Springs Rgnl Ap	frost-free	frost-free	365
Pomona	Glendora, San Dimas, Claremont, La Verne, Charter Oak	Pomona/fairplex	Jan 8	Dec 28	354
Poway	Rancho Santa Fe	Rancho Bernardo	frost-free	frost-free	365
Redwood	San Mateo, Woodside, San Carlos, Belmont, Foster, Emerald Lake Hills	Redwood City	Jan 17	Dec 12	333
Richmond	Berkeley, Tiburon, El Cerrito, El Sobrante, Kensington	Richmond	frost-free	frost-free	365
Riverside	San Bernardino, Rancho Cucamonga, Fontana, Jurupa Valley, Corona, Rialto, +7 more	Riverside Muni Ap	Jan 9	Dec 30	362
San Bernardino *	Redlands, Highland, Loma Linda, Mentone, Muscoy	Redlands	Jan 27	Dec 19	329
San Buenaventura (Ventura)	—	Oxnard Ventura Co Ap	frost-free	frost-free	365
San Diego	Jamul, Harbison Canyon, Eucalyptus Hills	El Cajon	Jan 6	Dec 21	350
San Jose	Fremont, Santa Clara, Milpitas	San Jose	Jan 12	Dec 22	347
San Marcos	Elfin Forest, Del Dios	Escondido #2	frost-free	frost-free	365
San Rafael	Lagunitas-Forest Knolls, Woodacre	San Rafael Civic Ctr	Jan 11	Dec 21	349
Santa Clarita	Stevenson Ranch	Newhall 5nw	frost-free	frost-free	365
Santa Paula	Oak View, Fillmore	Ojai	Mar 21	Nov 15	235
Sausalito	—	San Francisco Dwtn	frost-free	frost-free	365
Sea Ranch	Timber Cove	Ft Ross	Feb 26	Dec 27	310
Sea Ranch	—	Cloverdale	Feb 25	Dec 3	279
Seaside	Monterey, Del Monte Forest, Pacific Grove, Carmel-by-the-Sea, Del Rey Oaks	Monterey	frost-free	frost-free	365
Sunnyvale	Mountain View, East Palo Alto	Moffett Federal Airfield	Jan 6	Dec 23	353
Thousand Oaks	Camarillo, Moorpark, Somis, Casa Conejo	Camarillo Ap	frost-free	frost-free	365
Vandenberg AFB	Lompoc, Buellton	Lompoc	Jan 20	Dec 19	335
West Covina	Industry, Covina	San Gabriel Fire Dept	frost-free	frost-free	365
Wildomar	Lakeland	Elsinore	Jan 28	Dec 18	329

* San Bernardino is this group's median-season location — the calendar below is computed from its data.

Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.

Planting calendar (San Bernardino, representative)

Computed from San Bernardino's average frost dates — the median-season location in this Californiazone 10a group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).

Crop

JanFebMarAprMayJunJulAugSepOctNovDec

Tomato

Pepper

Cucumber

Summer squash / zucchini

Start indoors
Plant out
Fall sowing
First harvest

Planting windows for San Bernardino (California, zone 10a), this group's representative location.
Crop	Frost tolerance	Start indoors	Plant out	First harvest	Fall planting	Season fit
Tomato	Tender	Jan 1	Feb 3 – Feb 10	Apr 4 – Apr 24	—	matures comfortably
Pepper	Very tender	Jan 1	Feb 10 – Feb 17	Apr 11 – May 11	—	matures comfortably
Cucumber	Tender	Jan 1 – Jan 6	Feb 3 – Feb 10	Mar 25 – Apr 14	—	matures comfortably
Summer squash / zucchini	Tender	—	Feb 3 – Feb 10	Mar 20 – Apr 4	—	matures comfortably
Bush bean	Tender	—	Feb 3 – Feb 10	Mar 25 – Apr 4	Oct 20 – Oct 30	matures comfortably
Sweet corn	Tender	—	Jan 27 – Feb 10	Mar 28 – Apr 27	—	matures comfortably
Basil	Very tender	Jan 1	Feb 3 – Feb 10	Mar 5 – Mar 20	—	matures comfortably
Lettuce	Half-hardy	Jan 1	Jan 1 – Jan 13	Feb 15 – Mar 2	Oct 6 – Oct 21	matures comfortably
Pea	Hardy	—	Jan 1	Feb 25 – Mar 12	Sep 26 – Oct 11	matures comfortably
Spinach	Hardy	—	Jan 1	Feb 10 – Feb 20	Oct 16 – Oct 26	matures comfortably
Carrot	Half-hardy	—	Jan 6 – Jan 13	Mar 7 – Mar 27	Sep 16 – Oct 6	matures comfortably
Broccoli	Half-hardy	Jan 1	Jan 1 – Jan 13	Feb 25 – Mar 17	Sep 21 – Oct 11	matures comfortably

Which crops fit this growing season

Using San Bernardino's own 329-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.

Frost & freeze dates (San Bernardino)

From NOAA's 1991–2020 Climate Normals at station USC00047306. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.

Freeze probabilities by temperature threshold (MM/DD, NOAA 1991–2020), San Bernardino.
Threshold	Last spring — avg	Last spring — 90%-safe	First fall — avg	First fall — 90%-safe	Season (days)
36°F	Mar 2	Apr 5	Dec 2	Dec 19	272
32°F (freeze)	Jan 27	Feb 28	Dec 19	Jan 26	329
28°F	Jan 7	Feb 15	Jan 1	Feb 13	365
24°F	—	—	—	—	365

Growing degree days

Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 71 locations is 4,098; San Bernardino's own reading is shown below.

Annual growing degree days for San Bernardino (°F·days, NOAA 1991–2020).
Model	°F·days	Used for
Base 50°F (warm-season)	5,663	standard warm-season base (tomato, corn, beans)
Base 40°F (cool-season)	9,229	cool-season crops (brassicas, greens)

Hardiness zone 10a in California

Zone 10a means an average annual extreme minimum winter temperature of about 30 to 35 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. California spans 12 hardiness zones in this dataset — see all California locations for the full range, including zones5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10b, 11a.

Explore zone 10a in other states at zone 10a, or see all USDA hardiness zones.

Frequently asked questions

What does USDA hardiness zone 10a mean in California?: Zone 10a means an average annual extreme minimum winter temperature of 30 to 35 °F — the standard USDA measure of which perennials survive winter. 71 locations in California fall in this zone. It does not set planting dates; see the frost calendar below for that.
Where in California's zone 10a is the growing season longest?: Los Angeles runs the longest season on this page at about 364 days; Glendora is shortest at about 199 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
When should I plant tomatoes in California's zone 10a?: Using San Bernardino's frost dates (this page's median-season location): start seeds indoors about Jan 1, then transplant outside about Feb 3 – Feb 10. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
Does every location in California's zone 10a have the same frost dates?: No — they do not all share a weather station, so frost dates vary by a week or more across the 71 locations listed (see the table above for each location's own dates).

Sources & method

Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.