Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 96091 — Trinity Center, CA

ZIP code 96091 (Trinity Center, Trinity County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 27 and the first fall frost October 21.

Where ZIP 96091 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.

Zone7b5 to 10 °F

Coldest night−15 to −12.2 °C

Last frostApr 27

First frostOct 21

2012 zone8a

Was 8a on the 2012 map — half a zone colder now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 7b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Trinity Center, 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 Trinity Center, CA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 27median — 50% chance of a later frost

Safe for tender plantsMay 17only 10% chance of frost after

First fall frostOctober 21median — 10% chance by Oct 7

Growing season176 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 2 and returns around November 6.

From the NOAA station Cecilville, CA — 19 miles away, elevation 2,310 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 96091

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 16 – Mar 30

SpinachSow outdoors · Mar 16 – Apr 6

Broccoli, cabbageStart indoors · Feb 16 – Mar 2

Broccoli, cabbageTransplant · Apr 6 – Apr 20

Onion setsPlant outdoors · Mar 30 – Apr 13

PotatoesPlant outdoors · Apr 6 – Apr 20

LettuceSow outdoors · Mar 30 – Apr 13

Carrots, beetsSow outdoors · Apr 6 – Apr 20

TomatoesStart indoors · Mar 2 – Mar 16

TomatoesTransplant · May 4 – May 18

Peppers, eggplantStart indoors · Feb 16 – Mar 2

Peppers, eggplantTransplant · May 11 – May 25

BeansSow outdoors · May 4 – May 18

Sweet cornSow outdoors · May 4 – May 18

Cucumbers, squashSow outdoors · May 4 – May 18

Fall lettuce, spinachSow outdoors · Aug 26 – Sep 9

GarlicPlant cloves · Oct 7 – Nov 11

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 27) and first fall frost (Oct 21) 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 96091 came on Feb 27 — 43 days earlier than the 1991–2020 average (Apr 11).

average
Apr 112026
Feb 27

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 Trinity Center, CA

The soil mapped at the center of ZIP 96091 is Lithic Xerochrepts — very gravelly loam, somewhat excessively drained.

TextureVery gravelly loama good balance for most vegetables

pH5.8moderately acidic; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter4%moderate

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Rock outcrop-Lithic Xerochrepts-Typic Xerochrepts association, gently sloping to steep..

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 96091; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Trinity Center, CA

Summer high96 °Faverage high, July

Winter low30 °Faverage low, January

Hot days73days a year at 90 °F or more

Freezing nights101nights a year at 32 °F or less

Growing degree days2,974base 50 °F — the season’s usable heat

Longest day15 h 08 mindaylight on June 21

Shortest day9 h 13 mindaylight on December 21

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

Precipitation50.2 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: Cecilville, CA (19 mi away); precipitation: Trinity Center 0.6 Ese, CA (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

960488b

Junction City, CA · 19 mi

960938b

Weaverville, CA · 21 mi

960318b

Forks Of Salmon, CA · 23 mi

960108b

Big Bar, CA · 24 mi

960339a

French Gulch, CA · 24 mi

California planting zones →

Questions about 96091

What planting zone is ZIP code 96091?

ZIP code 96091 (Trinity Center, CA) is in USDA hardiness zone 7b on the 2023 map: the coldest night of an average winter reaches 5 to 10 °F (−15 to −12.2 °C).

When is the last frost in Trinity Center, CA?

The median last spring frost (32 °F) near 96091 is April 27; after May 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Cecilville station.

When is the first frost in Trinity Center, CA?

The median first fall frost near 96091 is October 21, giving a median frost-free growing season of 176 days.

When should I plant tomatoes in 96091?

Start tomato seeds indoors around Mar 2 – Mar 16 and set transplants outside around May 4 – May 18, one to three weeks after the median last frost.

How much rain and snow does 96091 get?

About 50.2 inches of precipitation a year (NOAA 1991–2020 normals, Trinity Center 0.6 Ese station).

How hot do summers get in Trinity Center, CA?

The average high peaks at 96 °F in July, with about 73 days a year at 90 °F or more.

What kind of soil does 96091 have?

The USDA soil survey maps Lithic Xerochrepts at the center of ZIP 96091: very gravelly loam, somewhat excessively drained, pH about 5.8 (moderately acidic).

Did spring come early in Trinity Center, CA in 2026?

Spring leaf-out near 96091 came on Feb 27 in 2026, 43 days earlier than the 1991–2020 average (Apr 11), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Trinity Center, CA?

Long-day onions: the longest day near 96091 is 15 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 96091 change?

Yes. The 2012 USDA map put 96091 in zone 8a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.