Planting zone for 92128 — San Diego, CA
ZIP code 92128 (San Diego, San Diego County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.
Where ZIP 92128 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.
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 ServiceLoading the forecast for San Diego, 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 Rancho Bernardo, CA — 2 miles away, elevation 689 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 92128 came on Jan 17 — 5 days earlier than the 1991–2020 average (Jan 22).
Jan 222026
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 San Diego, CA
The soil mapped at the center of ZIP 92128 is Linne — clay loam, well drained.
Map unit: Linne clay loam, 9 to 30 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 92128; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in San Diego, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Rancho Bernardo, CA (2 mi away); precipitation: Rancho Bernardo 0.5se, CA (within 1 mile). 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.
All 73 ZIP codes in San Diego → · California planting zones →
Questions about 92128
What planting zone is ZIP code 92128?
ZIP code 92128 (San Diego, 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 92128 get?
About 14.6 inches of precipitation a year (NOAA 1991–2020 normals, Rancho Bernardo 0.5se station).
How hot do summers get in San Diego, CA?
The average high peaks at 83 °F in August, with about 21 days a year at 90 °F or more.
What kind of soil does 92128 have?
The USDA soil survey maps Linne at the center of ZIP 92128: clay loam, well drained, pH about 8.2 (alkaline).
Did spring come early in San Diego, CA in 2026?
Spring leaf-out near 92128 came on Jan 17 in 2026, 5 days earlier than the 1991–2020 average (Jan 22), according to the USA National Phenology Network Spring Index.
What kind of onions grow in San Diego, CA?
Intermediate onions: the longest day near 92128 is 14 h 20 min, so day-neutral types bulb best; long-day varieties may not bulb fully.