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

Planting zone for 96101 — Alturas, CA

ZIP code 96101 (Alturas, Modoc County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is June 3 and the first fall frost September 13.

Where ZIP 96101 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostJun 3
First frostSep 13
2012 zone6a

Was 6a on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Alturas, 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 Alturas, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostJune 3median — 50% chance of a later frost
Safe for tender plantsJune 26only 10% chance of frost after
First fall frostSeptember 13median — 10% chance by Aug 27
Growing season97 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 14 and returns around September 27.

From the NOAA station Alturas, CA — 3 miles away, elevation 4,377 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 96101

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 22 – May 6
SpinachSow outdoors · Apr 22 – May 13
Broccoli, cabbageStart indoors · Mar 25 – Apr 8
Broccoli, cabbageTransplant · May 13 – May 27
Onion setsPlant outdoors · May 6 – May 20
PotatoesPlant outdoors · May 13 – May 27
LettuceSow outdoors · May 6 – May 20
Carrots, beetsSow outdoors · May 13 – May 27
TomatoesStart indoors · Apr 8 – Apr 22
TomatoesTransplant · Jun 10 – Jun 24
Peppers, eggplantStart indoors · Mar 25 – Apr 8
Peppers, eggplantTransplant · Jun 17 – Jul 1
BeansSow outdoors · Jun 10 – Jun 24
Sweet cornSow outdoors · Jun 10 – Jun 24
Cucumbers, squashSow outdoors · Jun 10 – Jun 24
Fall lettuce, spinachSow outdoors · Jul 19 – Aug 2
GarlicPlant cloves · Aug 30 – Oct 4
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 3) and first fall frost (Sep 13) 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 96101 came on Mar 10 — 20 days earlier than the 1991–2020 average (Mar 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 Alturas, CA

The soil mapped at the center of ZIP 96101 is Goose Lake — silt loam, poorly drained.

TextureSilt loama good balance for most vegetables
pH6.7neutral; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter13%high
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Goose Lake silt loam.

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 96101; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Alturas, CA

Summer high90 °Faverage high, July
Winter low21 °Faverage low, January
Hot days41days a year at 90 °F or more
Freezing nights204nights a year at 32 °F or less
Growing degree days1,936base 50 °F — the season’s usable heat
Longest day15 h 11 mindaylight on June 21
Shortest day9 h 10 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation11.7 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 44 °F, low 21 °F 44°21° JanFebruary: average high 47 °F, low 23 °F 47°23° FebMarch: average high 53 °F, low 27 °F 53°27° MarApril: average high 59 °F, low 31 °F 59°31° AprMay: average high 70 °F, low 37 °F 70°37° MayJune: average high 79 °F, low 42 °F 79°42° JunJuly: average high 90 °F, low 46 °F 90°46° JulAugust: average high 88 °F, low 44 °F 88°44° AugSeptember: average high 81 °F, low 38 °F 81°38° SepOctober: average high 67 °F, low 31 °F 67°31° OctNovember: average high 52 °F, low 25 °F 52°25° NovDecember: average high 42 °F, low 23 °F 42°23° Dec

Precipitation by month inches

0″1″2″January: 1.49 in precipitation 1.5 JanFebruary: 0.98 in precipitation 1.0 FebMarch: 1.22 in precipitation 1.2 MarApril: 1.21 in precipitation 1.2 AprMay: 1.39 in precipitation 1.4 MayJune: 0.71 in precipitation 0.7 JunJuly: 0.23 in precipitation 0.2 JulAugust: 0.30 in precipitation 0.3 AugSeptember: 0.37 in precipitation 0.4 SepOctober: 0.94 in precipitation 0.9 OctNovember: 1.39 in precipitation 1.4 NovDecember: 1.51 in precipitation 1.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Alturas, CA (3 mi away); precipitation: Alturas, CA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

961166b
Likely, CA · 14 mi
960157a
Canby, CA · 19 mi
961046b
Cedarville, CA · 20 mi
961086b
Davis Creek, CA · 24 mi
961106b
Eagleville, CA · 25 mi
961156b
Lake City, CA · 28 mi
960067a
Adin, CA · 28 mi
961196b
Madeline, CA · 29 mi

California planting zones →

Questions about 96101

What planting zone is ZIP code 96101?

ZIP code 96101 (Alturas, CA) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Alturas, CA?

The median last spring frost (32 °F) near 96101 is June 3; after June 26 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Alturas station.

When is the first frost in Alturas, CA?

The median first fall frost near 96101 is September 13, giving a median frost-free growing season of 97 days.

When should I plant tomatoes in 96101?

Start tomato seeds indoors around Apr 8 – Apr 22 and set transplants outside around Jun 10 – Jun 24, one to three weeks after the median last frost.

How much rain and snow does 96101 get?

About 11.7 inches of precipitation a year (NOAA 1991–2020 normals, Alturas station).

How hot do summers get in Alturas, CA?

The average high peaks at 90 °F in July, with about 41 days a year at 90 °F or more.

What kind of soil does 96101 have?

The USDA soil survey maps Goose Lake at the center of ZIP 96101: silt loam, poorly drained, pH about 6.7 (neutral).

Did spring come early in Alturas, CA in 2026?

Spring leaf-out near 96101 came on Mar 10 in 2026, 20 days earlier than the 1991–2020 average (Mar 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Alturas, CA?

Long-day onions: the longest day near 96101 is 15 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 96101 change?

Yes. The 2012 USDA map put 96101 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.