Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 30, 2026

Planting zone for Arcata, CA

Arcata, CA is in USDA zone 9b across its 2 ZIP codes. The median last spring frost is February 22 and the first fall frost December 7.

Arcata on the zone map

Outlined: its 1 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone9b25 to 30 °F

ZIP codes2

Last frostFeb 22

First frostDec 7

Growing season293 days

9b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Arcata, CA

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostFebruary 22median — 50% chance of a later frost

Safe for tender plantsMarch 23only 10% chance of frost after

First fall frostDecember 7median — 10% chance by Nov 15

Growing season293 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 3 and returns around December 25.

From the NOAA station Eureka WFO Woodley Island, CA, elevation 20 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in Arcata

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 11 – Jan 25

SpinachSow outdoors · Jan 11 – Feb 1

Broccoli, cabbageStart indoors · Dec 14 – Dec 28

Broccoli, cabbageTransplant · Feb 1 – Feb 15

Onion setsPlant outdoors · Jan 25 – Feb 8

PotatoesPlant outdoors · Feb 1 – Feb 15

LettuceSow outdoors · Jan 25 – Feb 8

Carrots, beetsSow outdoors · Feb 1 – Feb 15

TomatoesStart indoors · Dec 28 – Jan 11

TomatoesTransplant · Mar 1 – Mar 15

Peppers, eggplantStart indoors · Dec 14 – Dec 28

Peppers, eggplantTransplant · Mar 8 – Mar 22

BeansSow outdoors · Mar 1 – Mar 15

Sweet cornSow outdoors · Mar 1 – Mar 15

Cucumbers, squashSow outdoors · Mar 1 – Mar 15

Fall lettuce, spinachSow outdoors · Oct 12 – Oct 26

GarlicPlant cloves · Nov 23 – Dec 28

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 22) and first fall frost (Dec 7) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 95518 came on Jan 30 — about the same time as the 1991–2020 average (Jan 31).

average
Jan 312026
Jan 30

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Soil in Arcata, CA

The soil mapped at the center of ZIP 95518 is Timmons — loam, well drained.

TextureLoama good balance for most vegetables

pH5.2strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter8%high

Hydrologic groupCwater soaks in slowly

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Timmons and Lepoil soils, 0 to 2 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 95518; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Arcata, CA

Summer high64 °Faverage high, August

Winter low40 °Faverage low, December

Hot days0days a year at 90 °F or more

Freezing nights8nights a year at 32 °F or less

Growing degree days1,415base 50 °F — the season’s usable heat

Longest day15 h 07 mindaylight on June 21

Shortest day9 h 14 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation45.4 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Eureka WFO Woodley Island, CA (6 mi away); precipitation: Arcata 0.9 Wnw, CA (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Arcata

California planting zones →

Questions about Arcata

What planting zone is Arcata, CA?

Arcata, CA is in USDA hardiness zone 9b on the 2023 map (9b: 25 to 30 °F).

When is the last frost in Arcata, CA?

The median last spring frost is February 22 and the median first fall frost is December 7 (NOAA 1991–2020 normals, Eureka WFO Woodley Island station).

When can I plant a garden in Arcata, CA?

Cool-season crops like peas and spinach go in around Jan 11 – Feb 1; tomatoes, peppers, beans and squash after about Mar 1, once frost risk has passed.

What kind of onions grow in Arcata, CA?

Long-day onions: the longest day is 15 h 07 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Arcata, CA get?

About 45.4 inches of precipitation a year (NOAA 1991–2020 normals).