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

Planting zone for 92366 — Mountain Pass, CA

ZIP code 92366 (Mountain Pass, San Bernardino County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is March 17 and the first fall frost November 20.

Where ZIP 92366 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.

Zone8b15 to 20 °F
Coldest night−9.4 to −6.7 °C
Last frostMar 17
First frostNov 20
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 Mountain Pass, 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 Mountain Pass, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 17median — 50% chance of a later frost
Safe for tender plantsApril 11only 10% chance of frost after
First fall frostNovember 20median — 10% chance by Nov 4
Growing season245 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 26 and returns around December 1.

From the NOAA station Goodsprings, NV — 26 miles away, elevation 3,717 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 92366

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 3 – Feb 17
SpinachSow outdoors · Feb 3 – Feb 24
Broccoli, cabbageStart indoors · Jan 6 – Jan 20
Broccoli, cabbageTransplant · Feb 24 – Mar 10
Onion setsPlant outdoors · Feb 17 – Mar 3
PotatoesPlant outdoors · Feb 24 – Mar 10
LettuceSow outdoors · Feb 17 – Mar 3
Carrots, beetsSow outdoors · Feb 24 – Mar 10
TomatoesStart indoors · Jan 20 – Feb 3
TomatoesTransplant · Mar 24 – Apr 7
Peppers, eggplantStart indoors · Jan 6 – Jan 20
Peppers, eggplantTransplant · Mar 31 – Apr 14
BeansSow outdoors · Mar 24 – Apr 7
Sweet cornSow outdoors · Mar 24 – Apr 7
Cucumbers, squashSow outdoors · Mar 24 – Apr 7
Fall lettuce, spinachSow outdoors · Sep 25 – Oct 9
GarlicPlant cloves · Nov 6 – Dec 11
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 17) and first fall frost (Nov 20) 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 92366 came on Feb 5 — 18 days earlier than the 1991–2020 average (Feb 23).

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 Mountain Pass, CA

The soil mapped at the center of ZIP 92366 is Ferrogold — very gravelly fine sandy loam, well drained.

TextureVery gravelly fine sandy loamdrains and warms fast; dries out and needs more feeding
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Ferrogold very gravelly fine sandy loam, 4 to 15 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 92366; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mountain Pass, CA

Summer high102 °Faverage high, July
Winter low32 °Faverage low, January
Hot days128days a year at 90 °F or more
Freezing nights56nights a year at 32 °F or less
Growing degree days5,457base 50 °F — the season’s usable heat
Longest day14 h 33 mindaylight on June 21
Shortest day9 h 45 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation6.6 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 55 °F, low 32 °F 55°32° JanFebruary: average high 59 °F, low 35 °F 59°35° FebMarch: average high 67 °F, low 39 °F 67°39° MarApril: average high 75 °F, low 45 °F 75°45° AprMay: average high 87 °F, low 54 °F 87°54° MayJune: average high 98 °F, low 62 °F 98°62° JunJuly: average high 102 °F, low 69 °F 102°69° JulAugust: average high 100 °F, low 66 °F 100°66° AugSeptember: average high 91 °F, low 60 °F 91°60° SepOctober: average high 78 °F, low 50 °F 78°50° OctNovember: average high 63 °F, low 38 °F 63°38° NovDecember: average high 54 °F, low 32 °F 54°32° Dec

Precipitation by month inches

0″1″2″January: 0.90 in precipitation 0.9 JanFebruary: 1.19 in precipitation 1.2 FebMarch: 0.74 in precipitation 0.7 MarApril: 0.43 in precipitation 0.4 AprMay: 0.05 in precipitation 0.1 MayJune: 0.02 in precipitation 0.0 JunJuly: 0.79 in precipitation 0.8 JulAugust: 0.58 in precipitation 0.6 AugSeptember: 0.33 in precipitation 0.3 SepOctober: 0.55 in precipitation 0.6 OctNovember: 0.31 in precipitation 0.3 NovDecember: 0.69 in precipitation 0.7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Goodsprings, NV (26 mi away); precipitation: Goodsprings, NV (26 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

923648b
Nipton, CA · 10 mi
923238b
Cima, CA · 16 mi
890198b
Jean, NV · 21 mi
890269a
Jean, NV · 24 mi
891799a
Las Vegas, NV · 32 mi
890549a
Sloan, NV · 37 mi
923099a
Baker, CA · 38 mi
891789a
Las Vegas, NV · 38 mi

California planting zones →

Questions about 92366

What planting zone is ZIP code 92366?

ZIP code 92366 (Mountain Pass, 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 Mountain Pass, CA?

The median last spring frost (32 °F) near 92366 is March 17; after April 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Goodsprings station.

When is the first frost in Mountain Pass, CA?

The median first fall frost near 92366 is November 20, giving a median frost-free growing season of 245 days.

When should I plant tomatoes in 92366?

Start tomato seeds indoors around Jan 20 – Feb 3 and set transplants outside around Mar 24 – Apr 7, one to three weeks after the median last frost.

How much rain and snow does 92366 get?

About 6.6 inches of precipitation a year (NOAA 1991–2020 normals, Goodsprings station).

How hot do summers get in Mountain Pass, CA?

The average high peaks at 102 °F in July, with about 128 days a year at 90 °F or more.

What kind of soil does 92366 have?

The USDA soil survey maps Ferrogold at the center of ZIP 92366: very gravelly fine sandy loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Mountain Pass, CA in 2026?

Spring leaf-out near 92366 came on Feb 5 in 2026, 18 days earlier than the 1991–2020 average (Feb 23), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Mountain Pass, CA?

Intermediate onions: the longest day near 92366 is 14 h 33 min, so day-neutral types bulb best; long-day varieties may not bulb fully.