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

Planting zone for 90721 — Los Alamitos, CA

ZIP code 90721 (Los Alamitos, Orange County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 90721 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.

Zone10a30 to 35 °F
Coldest night−1.1 to 1.7 °C
Last frostrare
First frostrare
2012 zone10b

Was 10b on the 2012 map — half a zone colder now. 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 Los Alamitos, 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 Torrance Airport, CA — 16 miles away, elevation 89 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 90721 came on Jan 18 — 3 days earlier than 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 Los Alamitos, CA

The soil mapped at the center of ZIP 90721 is Bolsa — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables
pH8.0alkaline; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter0.25%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Bolsa silt loam, drained.

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 90721; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Los Alamitos, CA

Summer high83 °Faverage high, August
Winter low47 °Faverage low, January
Hot days23days a year at 90 °F or more
Freezing nights0nights a year at 32 °F or less
Growing degree days5,476base 50 °F — the season’s usable heat
Longest day14 h 24 mindaylight on June 21
Shortest day9 h 54 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation12 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 67 °F, low 48 °F 67°48° FebMarch: average high 69 °F, low 51 °F 69°51° MarApril: average high 71 °F, low 54 °F 71°54° AprMay: average high 73 °F, low 58 °F 73°58° MayJune: average high 76 °F, low 61 °F 76°61° JunJuly: average high 81 °F, low 65 °F 81°65° JulAugust: average high 83 °F, low 66 °F 83°66° AugSeptember: average high 82 °F, low 64 °F 82°64° SepOctober: average high 78 °F, low 59 °F 78°59° OctNovember: average high 73 °F, low 52 °F 73°52° NovDecember: average high 67 °F, low 47 °F 67°47° Dec

Precipitation by month inches

0″1″2″3″4″January: 2.89 in precipitation 2.9 JanFebruary: 3.02 in precipitation 3.0 FebMarch: 1.65 in precipitation 1.6 MarApril: 0.56 in precipitation 0.6 AprMay: 0.26 in precipitation 0.3 MayJune: 0.07 in precipitation 0.1 JunJuly: 0.05 in precipitation 0.1 JulAugust: 0.01 in precipitation 0.0 AugSeptember: 0.08 in precipitation 0.1 SepOctober: 0.53 in precipitation 0.5 OctNovember: 0.75 in precipitation 0.8 NovDecember: 2.15 in precipitation 2.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Long Beach Daugherty Field, CA (4 mi away); precipitation: Long Beach Daugherty Field, CA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 10a.

9072010a
Los Alamitos, CA · <1 mi
9071610a
Hawaiian Gardens, CA · 2 mi
9063010a
Cypress, CA · 2 mi
9284610a
Garden Grove, CA · 2 mi
9081510a
Long Beach, CA · 3 mi
9071510a
Lakewood, CA · 3 mi
9284510a
Garden Grove, CA · 3 mi
9080810a
Long Beach, CA · 3 mi

All 2 ZIP codes in Los Alamitos → · California planting zones →

Questions about 90721

What planting zone is ZIP code 90721?

ZIP code 90721 (Los Alamitos, 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 90721 get?

About 12 inches of precipitation a year (NOAA 1991–2020 normals, Long Beach Daugherty Field station).

How hot do summers get in Los Alamitos, CA?

The average high peaks at 83 °F in August, with about 23 days a year at 90 °F or more.

What kind of soil does 90721 have?

The USDA soil survey maps Bolsa at the center of ZIP 90721: silt loam, somewhat poorly drained, pH about 8.0 (alkaline).

Did spring come early in Los Alamitos, CA in 2026?

Spring leaf-out near 90721 came on Jan 18 in 2026, 3 days earlier than the 1991–2020 average (Jan 21), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Los Alamitos, CA?

Intermediate onions: the longest day near 90721 is 14 h 24 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 90721 change?

Yes. The 2012 USDA map put 90721 in zone 10b; the 2023 map puts it in zone 10a. The newer map uses 1991–2020 data and more weather stations.