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

Planting zone for 92251 — Imperial, CA

ZIP code 92251 (Imperial, Imperial County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 92251 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.

Zone10a30 to 35 °F
Coldest night−1.1 to 1.7 °C
Last frostrare
First frostrare
2012 zone10a

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 10a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Imperial, 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

A 32 °F frost doesn't happen here in most winters. At the nearest station (NOAA station El Centro Naf, CA — 4 miles away, elevation -43 ft) the median growing season is 347 days. When frost does come, it is a midwinter night or two; cover tender plants when a freeze is forecast.

Frost data: NOAA NCEI U.S. Climate Normals 1991–2020.

When spring arrived in 2026

In 2026, spring leaf-out near 92251 came on Jan 19 — 3 days earlier than the 1991–2020 average (Jan 22).

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 Imperial, CA

The soil mapped at the center of ZIP 92251 is Imperial — silty clay loam, somewhat poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH8.4alkaline; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter0.3%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Imperial-Glenbar silty clay loams complex, 0 to 2 percent slopes, wet.

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 92251; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Imperial, CA

Summer high107 °Faverage high, July
Winter low41 °Faverage low, December
Hot days180days a year at 90 °F or more
Freezing nights4nights a year at 32 °F or less
Growing degree days8,674base 50 °F — the season’s usable heat
Longest day14 h 19 mindaylight on June 21
Shortest day9 h 59 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation5.1 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°110°120°32 °FJanuary: average high 71 °F, low 42 °F 71°42° JanFebruary: average high 74 °F, low 46 °F 74°46° FebMarch: average high 81 °F, low 51 °F 81°51° MarApril: average high 87 °F, low 56 °F 87°56° AprMay: average high 94 °F, low 62 °F 94°62° MayJune: average high 103 °F, low 69 °F 103°69° JunJuly: average high 107 °F, low 77 °F 107°77° JulAugust: average high 107 °F, low 78 °F 107°78° AugSeptember: average high 102 °F, low 72 °F 102°72° SepOctober: average high 91 °F, low 60 °F 91°60° OctNovember: average high 79 °F, low 48 °F 79°48° NovDecember: average high 69 °F, low 41 °F 69°41° Dec

Precipitation by month inches

0″1″2″January: 1.13 in precipitation 1.1 JanFebruary: 0.86 in precipitation 0.9 FebMarch: 0.77 in precipitation 0.8 MarApril: 0.20 in precipitation 0.2 AprMay: 0.13 in precipitation 0.1 MayJune: 0.57 in precipitation 0.6 JunJuly: 0.20 in precipitation 0.2 JulAugust: 0.22 in precipitation 0.2 AugSeptember: 0.26 in precipitation 0.3 SepOctober: 0.24 in precipitation 0.2 OctNovember: 0.19 in precipitation 0.2 NovDecember: 0.34 in precipitation 0.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: El Centro Naf, CA (4 mi away); precipitation: El Centro Naf, 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.

9227310a
Seeley, CA · 5 mi
9224410a
El Centro, CA · 5 mi
9224310a
El Centro, CA · 10 mi
922819b
Westmorland, CA · 14 mi
9223110a
Calexico, CA · 15 mi
9225910a
Ocotillo, CA · 16 mi
9224910a
Heber, CA · 17 mi
9223210a
Calexico, CA · 18 mi

California planting zones →

Questions about 92251

What planting zone is ZIP code 92251?

ZIP code 92251 (Imperial, CA) is in USDA hardiness zone 10a on the 2023 map: the coldest night of an average winter reaches 30 to 35 °F (−1.1 to 1.7 °C).

How much rain and snow does 92251 get?

About 5.1 inches of precipitation a year (NOAA 1991–2020 normals, El Centro Naf station).

How hot do summers get in Imperial, CA?

The average high peaks at 107 °F in July, with about 180 days a year at 90 °F or more.

What kind of soil does 92251 have?

The USDA soil survey maps Imperial at the center of ZIP 92251: silty clay loam, somewhat poorly drained, pH about 8.4 (alkaline).

Did spring come early in Imperial, CA in 2026?

Spring leaf-out near 92251 came on Jan 19 in 2026, 3 days earlier than the 1991–2020 average (Jan 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Imperial, CA?

Intermediate onions: the longest day near 92251 is 14 h 19 min, so day-neutral types bulb best; long-day varieties may not bulb fully.