Planting zone for 90623 — La Palma, CA
ZIP code 90623 (La Palma, Orange County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.
Where ZIP 90623 is
Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoomNot 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.
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 ServiceLoading the forecast for La Palma, 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 Gabriel Fire Dept, CA — 17 miles away, elevation 364 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 90623 came on Jan 17 — 4 days earlier than the 1991–2020 average (Jan 21).
Jan 212026
Jan 17
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 La Palma, CA
The soil mapped at the center of ZIP 90623 is Metz — loamy sand, somewhat excessively drained.
Map unit: Metz loamy sand, moderately fine substratum.
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 90623; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in La Palma, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Fullerton Municipal Airport, CA (4 mi away); precipitation: Fullerton Municipal Airport, CA (4 mi away). Daylight is calculated from latitude.
Nearby ZIP codes
All 8 nearest ZIP codes share zone 10a.
Questions about 90623
What planting zone is ZIP code 90623?
ZIP code 90623 (La Palma, 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 90623 get?
About 11.9 inches of precipitation a year (NOAA 1991–2020 normals, Fullerton Municipal Airport station).
How hot do summers get in La Palma, CA?
The average high peaks at 87 °F in August, with about 39 days a year at 90 °F or more.
What kind of soil does 90623 have?
The USDA soil survey maps Metz at the center of ZIP 90623: loamy sand, somewhat excessively drained, pH about 7.5 (slightly alkaline).
Did spring come early in La Palma, CA in 2026?
Spring leaf-out near 90623 came on Jan 17 in 2026, 4 days earlier than the 1991–2020 average (Jan 21), according to the USA National Phenology Network Spring Index.
What kind of onions grow in La Palma, CA?
Intermediate onions: the longest day near 90623 is 14 h 24 min, so day-neutral types bulb best; long-day varieties may not bulb fully.
Did the zone for 90623 change?
Yes. The 2012 USDA map put 90623 in zone 10b; the 2023 map puts it in zone 10a. The newer map uses 1991–2020 data and more weather stations.