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

Planting zone for 96017 — Castella, CA

ZIP code 96017 (Castella, Shasta County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is April 23 and the first fall frost October 27.

Where ZIP 96017 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.

Zone8b15 to 20 °F

Coldest night−9.4 to −6.7 °C

Last frostApr 23

First frostOct 27

2012 zone8b

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 8b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Castella, 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 Castella, CA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 23median — 50% chance of a later frost

Safe for tender plantsMay 12only 10% chance of frost after

First fall frostOctober 27median — 10% chance by Oct 9

Growing season185 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 31 and returns around November 12.

From the NOAA station Dunsmuir Trtmt Pl, CA — 6 miles away, elevation 2,169 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 96017

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 12 – Mar 26

SpinachSow outdoors · Mar 12 – Apr 2

Broccoli, cabbageStart indoors · Feb 12 – Feb 26

Broccoli, cabbageTransplant · Apr 2 – Apr 16

Onion setsPlant outdoors · Mar 26 – Apr 9

PotatoesPlant outdoors · Apr 2 – Apr 16

LettuceSow outdoors · Mar 26 – Apr 9

Carrots, beetsSow outdoors · Apr 2 – Apr 16

TomatoesStart indoors · Feb 26 – Mar 12

TomatoesTransplant · Apr 30 – May 14

Peppers, eggplantStart indoors · Feb 12 – Feb 26

Peppers, eggplantTransplant · May 7 – May 21

BeansSow outdoors · Apr 30 – May 14

Sweet cornSow outdoors · Apr 30 – May 14

Cucumbers, squashSow outdoors · Apr 30 – May 14

Fall lettuce, spinachSow outdoors · Sep 1 – Sep 15

GarlicPlant cloves · Oct 13 – Nov 17

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 23) and first fall frost (Oct 27) 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 96017 came on Feb 4 — 18 days earlier than the 1991–2020 average (Feb 22).

average
Feb 222026
Feb 4

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 Castella, CA

The soil mapped at the center of ZIP 96017 is Neuns family — very gravelly sandy loam, well drained.

TextureVery gravelly sandy loamdrains and warms fast; dries out and needs more feeding

pH6.6neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Neuns family, 40 to 60 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 96017; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Castella, CA

Summer high90 °Faverage high, July

Winter low30 °Faverage low, January

Hot days59days a year at 90 °F or more

Freezing nights105nights a year at 32 °F or less

Growing degree days2,829base 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)

Precipitation63.3 inper year, rain and melted snow

Snowfall27 inper year; 26 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Dunsmuir Trtmt Pl, CA (6 mi away); precipitation: Dunsmuir Trtmt Pl, CA (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Mount Shasta, CA · 15 mi

Montgomery Creek, CA · 24 mi

960917b

Trinity Center, CA · 26 mi

960709a

Obrien, CA · 26 mi

California planting zones →

Questions about 96017

What planting zone is ZIP code 96017?

ZIP code 96017 (Castella, CA) is in USDA hardiness zone 8b on the 2023 map: the coldest night of an average winter reaches 15 to 20 °F (−9.4 to −6.7 °C).

When is the last frost in Castella, CA?

The median last spring frost (32 °F) near 96017 is April 23; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Dunsmuir Trtmt Pl station.

When is the first frost in Castella, CA?

The median first fall frost near 96017 is October 27, giving a median frost-free growing season of 185 days.

When should I plant tomatoes in 96017?

Start tomato seeds indoors around Feb 26 – Mar 12 and set transplants outside around Apr 30 – May 14, one to three weeks after the median last frost.

How much rain and snow does 96017 get?

About 63.3 inches of precipitation a year and 27 inches of snowfall (NOAA 1991–2020 normals, Dunsmuir Trtmt Pl station).

How hot do summers get in Castella, CA?

The average high peaks at 90 °F in July, with about 59 days a year at 90 °F or more.

What kind of soil does 96017 have?

The USDA soil survey maps Neuns family at the center of ZIP 96017: very gravelly sandy loam, well drained, pH about 6.6 (neutral).

Did spring come early in Castella, CA in 2026?

Spring leaf-out near 96017 came on Feb 4 in 2026, 18 days earlier than the 1991–2020 average (Feb 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Castella, CA?

Long-day onions: the longest day near 96017 is 15 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).