Planting zone for 91306 — Winnetka, CA
ZIP code 91306 (Winnetka, Los Angeles County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F. The median last spring frost is January 24 and the first fall frost December 15.
Where ZIP 91306 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 9b on the 2012 map — half a zone warmer 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 Winnetka, 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 in Winnetka, CA
A hard freeze (28 °F) usually ends around December 31 and returns around December 26.
From the NOAA station Woodland Hills Pierce College, CA — 2 miles away, elevation 791 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.
When to plant vegetables in 91306
Counted from the median last spring frost (Jan 24) and first fall frost (Dec 15) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.
When spring arrived in 2026
In 2026, spring leaf-out near 91306 came on Jan 16 — 5 days earlier than the 1991–2020 average (Jan 21).
Jan 212026
Jan 16
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 Winnetka, CA
The soil mapped at the center of ZIP 91306 is San Emigdio — sandy loam, well drained.
Map unit: San Emigdio-Urban land complex, 0 to 2 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 91306; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in Winnetka, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Woodland Hills Pierce College, CA (2 mi away); precipitation: Woodland Hills Pierce College, CA (2 mi away). Daylight is calculated from latitude.
Nearby ZIP codes
2 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.
Questions about 91306
What planting zone is ZIP code 91306?
ZIP code 91306 (Winnetka, 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).
When is the last frost in Winnetka, CA?
The median last spring frost (32 °F) near 91306 is January 24; after March 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Woodland Hills Pierce College station.
When is the first frost in Winnetka, CA?
The median first fall frost near 91306 is December 15, giving a median frost-free growing season of 329 days.
When should I plant tomatoes in 91306?
Start tomato seeds indoors around Nov 29 – Dec 13 and set transplants outside around Jan 31 – Feb 14, one to three weeks after the median last frost.
How much rain and snow does 91306 get?
About 16.4 inches of precipitation a year (NOAA 1991–2020 normals, Woodland Hills Pierce College station).
How hot do summers get in Winnetka, CA?
The average high peaks at 97 °F in August, with about 115 days a year at 90 °F or more.
What kind of soil does 91306 have?
The USDA soil survey maps San Emigdio at the center of ZIP 91306: sandy loam, well drained, pH about 8.0 (alkaline).
Did spring come early in Winnetka, CA in 2026?
Spring leaf-out near 91306 came on Jan 16 in 2026, 5 days earlier than the 1991–2020 average (Jan 21), according to the USA National Phenology Network Spring Index.
What kind of onions grow in Winnetka, CA?
Intermediate onions: the longest day near 91306 is 14 h 26 min, so day-neutral types bulb best; long-day varieties may not bulb fully.
Did the zone for 91306 change?
Yes. The 2012 USDA map put 91306 in zone 9b; the 2023 map puts it in zone 10a. The newer map uses 1991–2020 data and more weather stations.