Planting zone for 93412 — Los Osos, CA
ZIP code 93412 (Los Osos, San Luis Obispo County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.
Where ZIP 93412 is
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 Los Osos, 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 Morro Bay Fire Dept, CA — 4 miles away, elevation 118 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 93412 came on Jan 19 — 6 days earlier than the 1991–2020 average (Jan 25).
Jan 252026
Jan 19
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 Osos, CA
The soil mapped at the center of ZIP 93412 is Baywood — fine sand, somewhat excessively drained.
Map unit: Baywood fine sand, 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 93412; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in Los Osos, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Morro Bay Fire Dept, CA (4 mi away); precipitation: Morro Bay Fire Dept, CA (4 mi away). Daylight is calculated from latitude.
Nearby ZIP codes
4 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.
Questions about 93412
What planting zone is ZIP code 93412?
ZIP code 93412 (Los Osos, 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 93412 get?
About 17 inches of precipitation a year (NOAA 1991–2020 normals, Morro Bay Fire Dept station).
How hot do summers get in Los Osos, CA?
The average high peaks at 73 °F in October, with about 1 days a year at 90 °F or more.
What kind of soil does 93412 have?
The USDA soil survey maps Baywood at the center of ZIP 93412: fine sand, somewhat excessively drained, pH about 6.2 (slightly acidic).
Did spring come early in Los Osos, CA in 2026?
Spring leaf-out near 93412 came on Jan 19 in 2026, 6 days earlier than the 1991–2020 average (Jan 25), according to the USA National Phenology Network Spring Index.
What kind of onions grow in Los Osos, CA?
Intermediate onions: the longest day near 93412 is 14 h 32 min, so day-neutral types bulb best; long-day varieties may not bulb fully.