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

Planting zone for 94561 — Oakley, CA

ZIP code 94561 (Oakley, Contra Costa County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F.

Where ZIP 94561 is

Outlined: the ZIP code area · 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.

Zone9b25 to 30 °F
Coldest night−3.9 to −1.1 °C
Last frostrare
First frostrare
2012 zone9b

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 9b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Oakley, 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 Antioch Pumping Plt #3, CA — 3 miles away, elevation 59 ft) the median growing season is 343 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 94561 came on Jan 31 — about the same time as the 1991–2020 average (Jan 30).

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 Oakley, CA

The soil mapped at the center of ZIP 94561 is Sycamore — silty clay loam, poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.8neutral; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter2.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Sycamore silty clay loam, 0 to 2 percent slopes, MLRA 17.

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 94561; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Oakley, CA

Summer high91 °Faverage high, July
Winter low40 °Faverage low, January
Hot days64days a year at 90 °F or more
Freezing nights7nights a year at 32 °F or less
Growing degree days4,827base 50 °F — the season’s usable heat
Longest day14 h 48 mindaylight on June 21
Shortest day9 h 31 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation12.6 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°32 °FJanuary: average high 56 °F, low 40 °F 56°40° JanFebruary: average high 61 °F, low 44 °F 61°44° FebMarch: average high 67 °F, low 47 °F 67°47° MarApril: average high 72 °F, low 50 °F 72°50° AprMay: average high 79 °F, low 54 °F 79°54° MayJune: average high 86 °F, low 59 °F 86°59° JunJuly: average high 91 °F, low 61 °F 91°61° JulAugust: average high 90 °F, low 60 °F 90°60° AugSeptember: average high 87 °F, low 59 °F 87°59° SepOctober: average high 78 °F, low 54 °F 78°54° OctNovember: average high 65 °F, low 46 °F 65°46° NovDecember: average high 56 °F, low 40 °F 56°40° Dec

Precipitation by month inches

0″1″2″3″January: 2.68 in precipitation 2.7 JanFebruary: 2.36 in precipitation 2.4 FebMarch: 1.95 in precipitation 1.9 MarApril: 0.91 in precipitation 0.9 AprMay: 0.38 in precipitation 0.4 MayJune: 0.11 in precipitation 0.1 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.02 in precipitation 0.0 AugSeptember: 0.06 in precipitation 0.1 SepOctober: 0.42 in precipitation 0.4 OctNovember: 1.18 in precipitation 1.2 NovDecember: 2.53 in precipitation 2.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Antioch Pumping Plt #3, CA (3 mi away); precipitation: Antioch Pumping Plt #3, CA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9b.

945489b
Knightsen, CA · 3 mi
945119b
Bethel Island, CA · 4 mi
945139b
Brentwood, CA · 5 mi
945319b
Antioch, CA · 5 mi
945099b
Antioch, CA · 7 mi
945059b
Discovery Bay, CA · 10 mi
952199b
Stockton, CA · 10 mi
945719b
Rio Vista, CA · 12 mi

California planting zones →

Questions about 94561

What planting zone is ZIP code 94561?

ZIP code 94561 (Oakley, CA) is in USDA hardiness zone 9b on the 2023 map: the coldest night of an average winter reaches 25 to 30 °F (−3.9 to −1.1 °C).

How much rain and snow does 94561 get?

About 12.6 inches of precipitation a year (NOAA 1991–2020 normals, Antioch Pumping Plt #3 station).

How hot do summers get in Oakley, CA?

The average high peaks at 91 °F in July, with about 64 days a year at 90 °F or more.

What kind of soil does 94561 have?

The USDA soil survey maps Sycamore at the center of ZIP 94561: silty clay loam, poorly drained, pH about 6.8 (neutral).

Did spring come early in Oakley, CA in 2026?

Spring leaf-out near 94561 came on Jan 31 in 2026, about the same as the 1991–2020 average (Jan 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Oakley, CA?

Intermediate onions: the longest day near 94561 is 14 h 48 min, so day-neutral types bulb best; long-day varieties may not bulb fully.