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

Planting zone for 95518 — Arcata, CA

ZIP code 95518 (Arcata, Humboldt County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is February 22 and the first fall frost December 7.

Where ZIP 95518 is

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
Coldest night−3.9 to −1.1 °C
Last frostFeb 22
First frostDec 7
2012 zone9b

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Arcata, CA…

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 — 6 miles away, 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 95518

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).

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

30°40°50°60°70°32 °FJanuary: average high 55 °F, low 41 °F 55°41° JanFebruary: average high 55 °F, low 41 °F 55°41° FebMarch: average high 56 °F, low 42 °F 56°42° MarApril: average high 57 °F, low 44 °F 57°44° AprMay: average high 60 °F, low 48 °F 60°48° MayJune: average high 62 °F, low 50 °F 62°50° JunJuly: average high 63 °F, low 52 °F 63°52° JulAugust: average high 64 °F, low 53 °F 64°53° AugSeptember: average high 64 °F, low 51 °F 64°51° SepOctober: average high 62 °F, low 47 °F 62°47° OctNovember: average high 58 °F, low 43 °F 58°43° NovDecember: average high 55 °F, low 40 °F 55°40° Dec

Precipitation by month inches

0″2″4″6″8″10″January: 6.40 in precipitation 6.4 JanFebruary: 6.56 in precipitation 6.6 FebMarch: 5.72 in precipitation 5.7 MarApril: 4.34 in precipitation 4.3 AprMay: 1.94 in precipitation 1.9 MayJune: 1.07 in precipitation 1.1 JunJuly: 0.23 in precipitation 0.2 JulAugust: 0.22 in precipitation 0.2 AugSeptember: 0.94 in precipitation 0.9 SepOctober: 2.94 in precipitation 2.9 OctNovember: 5.90 in precipitation 5.9 NovDecember: 9.11 in precipitation 9.1 Dec

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.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9b.

955219b
Arcata, CA · 3 mi
955249b
Bayside, CA · 4 mi
955019b
Eureka, CA · 6 mi
955199b
Mckinleyville, CA · 7 mi
955029b
Eureka, CA · 7 mi
955349b
Cutten, CA · 7 mi
955649b
Samoa, CA · 8 mi
955039b
Eureka, CA · 9 mi

All 2 ZIP codes in Arcata → · California planting zones →

Questions about 95518

What planting zone is ZIP code 95518?

ZIP code 95518 (Arcata, CA) is in USDA hardiness zone 9b on the 2023 map: the coldest night of an average winter reaches 25 to 30 °F (−3.9 to −1.1 °C).

When is the last frost in Arcata, CA?

The median last spring frost (32 °F) near 95518 is February 22; after March 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Eureka WFO Woodley Island station.

When is the first frost in Arcata, CA?

The median first fall frost near 95518 is December 7, giving a median frost-free growing season of 293 days.

When should I plant tomatoes in 95518?

Start tomato seeds indoors around Dec 28 – Jan 11 and set transplants outside around Mar 1 – Mar 15, one to three weeks after the median last frost.

How much rain and snow does 95518 get?

About 45.4 inches of precipitation a year (NOAA 1991–2020 normals, Arcata 0.9 Wnw station).

How hot do summers get in Arcata, CA?

The average high peaks at 64 °F in August, with about 0 days a year at 90 °F or more.

What kind of soil does 95518 have?

The USDA soil survey maps Timmons at the center of ZIP 95518: loam, well drained, pH about 5.2 (strongly acidic).

Did spring come early in Arcata, CA in 2026?

Spring leaf-out near 95518 came on Jan 30 in 2026, about the same as the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Arcata, CA?

Long-day onions: the longest day near 95518 is 15 h 07 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).