Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for West Covina, CA

West Covina, CA is in USDA zone 10a across its 4 ZIP codes.

West Covina on the zone map

Outlined: its 3 ZIP code areas · 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

ZIP codes4

Last frostrare

First frostrare

Growing seasonall year

10a 4 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for West Covina, 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, 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 91790 came on Jan 18 — about the same time as the 1991–2020 average (Jan 20).

average
Jan 202026
Jan 18

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 West Covina, CA

The soil mapped at the center of ZIP 91790 is Palmview — fine sandy loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding

pH7.1neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupBwater soaks in moderately

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Urban land-Palmview-Tujunga complex, 0 to 5 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 91790; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in West Covina, CA

Summer high88 °Faverage high, August

Winter low45 °Faverage low, December

Hot days65days a year at 90 °F or more

Freezing nights1nights a year at 32 °F or less

Growing degree days5,861base 50 °F — the season’s usable heat

Longest day14 h 26 mindaylight on June 21

Shortest day9 h 53 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation16.7 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: San Gabriel Fire Dept, CA (9 mi away); precipitation: Covina City Yard Fc387b, CA (4 mi away). Daylight is calculated from latitude.