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

Planting zone for 91932 — Imperial Beach, CA

ZIP code 91932 (Imperial Beach, San Diego County) is in USDA zone 10b: the coldest winter night averages 35 to 40 °F.

Where ZIP 91932 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.

Zone10b35 to 40 °F
Coldest night1.7 to 4.4 °C
Last frostrare
First frostrare
2012 zone10b

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 10b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Imperial Beach, 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 San Diego Brown Field, CA — 8 miles away, elevation 515 ft) the median growing season is 365 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 91932 came on Jan 20 — about the same time as the 1991–2020 average (Jan 21).

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 Beach, CA

The soil mapped at the center of ZIP 91932 is Huerhuero — loam, moderately well drained.

TextureLoama good balance for most vegetables
pH5.6moderately acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Huerhuero-Urban land complex, 2 to 9 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 91932; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Imperial Beach, CA

Summer high75 °Faverage high, August
Winter low46 °Faverage low, December
Hot days2days a year at 90 °F or more
Freezing nights0nights a year at 32 °F or less
Growing degree days4,519base 50 °F — the season’s usable heat
Longest day14 h 18 mindaylight on June 21
Shortest day10 h 00 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation8.6 inper year, rain and melted snow

Average high and low, by month

40°50°60°70°80°90°January: average high 67 °F, low 47 °F 67°47° JanFebruary: average high 65 °F, low 48 °F 65°48° FebMarch: average high 66 °F, low 51 °F 66°51° MarApril: average high 67 °F, low 53 °F 67°53° AprMay: average high 68 °F, low 57 °F 68°57° MayJune: average high 70 °F, low 60 °F 70°60° JunJuly: average high 73 °F, low 64 °F 73°64° JulAugust: average high 75 °F, low 65 °F 75°65° AugSeptember: average high 75 °F, low 62 °F 75°62° SepOctober: average high 73 °F, low 56 °F 73°56° OctNovember: average high 70 °F, low 50 °F 70°50° NovDecember: average high 66 °F, low 46 °F 66°46° Dec

Precipitation by month inches

0″1″2″3″January: 1.69 in precipitation 1.7 JanFebruary: 2.10 in precipitation 2.1 FebMarch: 1.85 in precipitation 1.9 MarApril: 0.59 in precipitation 0.6 AprMay: 0.10 in precipitation 0.1 MayJune: 0.08 in precipitation 0.1 JunJuly: 0.33 in precipitation 0.3 JulAugust: 0.03 in precipitation 0.0 AugSeptember: 0.14 in precipitation 0.1 SepOctober: 0.42 in precipitation 0.4 OctNovember: 0.80 in precipitation 0.8 NovDecember: 0.45 in precipitation 0.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Imperial Beach Ream Field NAS, CA (within 1 mile); precipitation: Imperial Beach Ream Field NAS, CA (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 10b.

9193310b
Imperial Beach, CA · 1 mi
9217310b
San Ysidro, CA · 4 mi
9191110b
Chula Vista, CA · 5 mi
9190910b
Chula Vista, CA · 5 mi
9191210b
Chula Vista, CA · 5 mi
9192110b
Chula Vista, CA · 5 mi
9191010b
Chula Vista, CA · 6 mi
9215510b
San Diego, CA · 7 mi

All 2 ZIP codes in Imperial Beach → · California planting zones →

Questions about 91932

What planting zone is ZIP code 91932?

ZIP code 91932 (Imperial Beach, CA) is in USDA hardiness zone 10b on the 2023 map: the coldest night of an average winter reaches 35 to 40 °F (1.7 to 4.4 °C).

How much rain and snow does 91932 get?

About 8.6 inches of precipitation a year (NOAA 1991–2020 normals, Imperial Beach Ream Field NAS station).

How hot do summers get in Imperial Beach, CA?

The average high peaks at 75 °F in August, with about 2 days a year at 90 °F or more.

What kind of soil does 91932 have?

The USDA soil survey maps Huerhuero at the center of ZIP 91932: loam, moderately well drained, pH about 5.6 (moderately acidic).

Did spring come early in Imperial Beach, CA in 2026?

Spring leaf-out near 91932 came on Jan 20 in 2026, about the same as the 1991–2020 average (Jan 21), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Imperial Beach, CA?

Short-day onions: the longest day near 91932 is 14 h 18 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.