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

Planting zone for 95570 — Trinidad, CA

ZIP code 95570 (Trinidad, Humboldt County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is March 8 and the first fall frost November 30.

Where ZIP 95570 is

Outlined: the ZIP code area · 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 frostMar 8
First frostNov 30
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 Trinidad, 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 Trinidad, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 8median — 50% chance of a later frost
Safe for tender plantsApril 15only 10% chance of frost after
First fall frostNovember 30median — 10% chance by Nov 1
Growing season262 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 20 and returns around December 24.

From the NOAA station Arcata Eureka Airport, CA — 9 miles away, elevation 200 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 95570

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 25 – Feb 8
SpinachSow outdoors · Jan 25 – Feb 15
Broccoli, cabbageStart indoors · Dec 28 – Jan 11
Broccoli, cabbageTransplant · Feb 15 – Mar 1
Onion setsPlant outdoors · Feb 8 – Feb 22
PotatoesPlant outdoors · Feb 15 – Mar 1
LettuceSow outdoors · Feb 8 – Feb 22
Carrots, beetsSow outdoors · Feb 15 – Mar 1
TomatoesStart indoors · Jan 11 – Jan 25
TomatoesTransplant · Mar 15 – Mar 29
Peppers, eggplantStart indoors · Dec 28 – Jan 11
Peppers, eggplantTransplant · Mar 22 – Apr 5
BeansSow outdoors · Mar 15 – Mar 29
Sweet cornSow outdoors · Mar 15 – Mar 29
Cucumbers, squashSow outdoors · Mar 15 – Mar 29
Fall lettuce, spinachSow outdoors · Oct 5 – Oct 19
GarlicPlant cloves · Nov 16 – Dec 21
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 8) and first fall frost (Nov 30) 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 95570 came on Jan 31 — 3 days earlier than the 1991–2020 average (Feb 3).

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 Trinidad, CA

The soil mapped at the center of ZIP 95570 is Coppercreek — 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 classNot prime farmlandUSDA classification

Map unit: Coppercreek-Slidecreek-Tectah complex, 30 to 50 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 95570; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Trinidad, CA

Summer high65 °Faverage high, August
Winter low40 °Faverage low, December
Hot days0days a year at 90 °F or more
Freezing nights19nights a year at 32 °F or less
Growing degree days1,374base 50 °F — the season’s usable heat
Longest day15 h 08 mindaylight on June 21
Shortest day9 h 12 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation58 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°32 °FJanuary: average high 56 °F, low 41 °F 56°41° JanFebruary: average high 57 °F, low 41 °F 57°41° FebMarch: average high 57 °F, low 41 °F 57°41° MarApril: average high 58 °F, low 43 °F 58°43° AprMay: average high 60 °F, low 46 °F 60°46° MayJune: average high 63 °F, low 49 °F 63°49° JunJuly: average high 63 °F, low 51 °F 63°51° JulAugust: average high 65 °F, low 51 °F 65°51° AugSeptember: average high 65 °F, low 49 °F 65°49° SepOctober: average high 64 °F, low 45 °F 64°45° OctNovember: average high 59 °F, low 42 °F 59°42° NovDecember: average high 56 °F, low 40 °F 56°40° Dec

Precipitation by month inches

0″2″4″6″8″10″January: 9.48 in precipitation 9.5 JanFebruary: 8.09 in precipitation 8.1 FebMarch: 8.02 in precipitation 8.0 MarApril: 4.83 in precipitation 4.8 AprMay: 2.50 in precipitation 2.5 MayJune: 1.08 in precipitation 1.1 JunJuly: 0.39 in precipitation 0.4 JulAugust: 0.25 in precipitation 0.3 AugSeptember: 1.72 in precipitation 1.7 SepOctober: 3.41 in precipitation 3.4 OctNovember: 7.26 in precipitation 7.3 NovDecember: 10.95 in precipitation 10.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Arcata Eureka Airport, CA (9 mi away); precipitation: Trinidad 1.0 Ene, CA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

1 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

955199b
Mckinleyville, CA · 11 mi
955559b
Orick, CA · 14 mi
955189b
Arcata, CA · 17 mi
955259a
Blue Lake, CA · 17 mi
955219b
Arcata, CA · 19 mi
955249b
Bayside, CA · 20 mi
955019b
Eureka, CA · 22 mi
955029b
Eureka, CA · 22 mi

California planting zones →

Questions about 95570

What planting zone is ZIP code 95570?

ZIP code 95570 (Trinidad, 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 Trinidad, CA?

The median last spring frost (32 °F) near 95570 is March 8; after April 15 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Arcata Eureka Airport station.

When is the first frost in Trinidad, CA?

The median first fall frost near 95570 is November 30, giving a median frost-free growing season of 262 days.

When should I plant tomatoes in 95570?

Start tomato seeds indoors around Jan 11 – Jan 25 and set transplants outside around Mar 15 – Mar 29, one to three weeks after the median last frost.

How much rain and snow does 95570 get?

About 58 inches of precipitation a year (NOAA 1991–2020 normals, Trinidad 1.0 Ene station).

How hot do summers get in Trinidad, CA?

The average high peaks at 65 °F in August, with about 0 days a year at 90 °F or more.

What kind of soil does 95570 have?

The USDA soil survey maps Coppercreek at the center of ZIP 95570: loam, well drained, pH about 5.2 (strongly acidic).

Did spring come early in Trinidad, CA in 2026?

Spring leaf-out near 95570 came on Jan 31 in 2026, 3 days earlier than the 1991–2020 average (Feb 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Trinidad, CA?

Long-day onions: the longest day near 95570 is 15 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).