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

Planting zone for 94523 — Pleasant Hill, CA

ZIP code 94523 (Pleasant Hill, Contra Costa County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F.

Where ZIP 94523 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 Pleasant Hill, 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 Concord Wwtp, CA — 2 miles away, elevation 39 ft) the median growing season is 346 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 94523 came on Jan 30 — 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 Pleasant Hill, CA

The soil mapped at the center of ZIP 94523 is Conejo — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH6.8neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Conejo clay loam, 0 to 2 percent slopes, MLRA 14.

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 94523; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Pleasant Hill, CA

Summer high88 °Faverage high, July
Winter low41 °Faverage low, December
Hot days47days a year at 90 °F or more
Freezing nights4nights a year at 32 °F or less
Growing degree days4,672base 50 °F — the season’s usable heat
Longest day14 h 48 mindaylight on June 21
Shortest day9 h 32 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation17.7 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°32 °FJanuary: average high 58 °F, low 42 °F 58°42° JanFebruary: average high 63 °F, low 44 °F 63°44° FebMarch: average high 68 °F, low 47 °F 68°47° MarApril: average high 72 °F, low 49 °F 72°49° AprMay: average high 78 °F, low 53 °F 78°53° MayJune: average high 85 °F, low 57 °F 85°57° JunJuly: average high 88 °F, low 58 °F 88°58° JulAugust: average high 88 °F, low 59 °F 88°59° AugSeptember: average high 86 °F, low 58 °F 86°58° SepOctober: average high 78 °F, low 53 °F 78°53° OctNovember: average high 67 °F, low 46 °F 67°46° NovDecember: average high 59 °F, low 41 °F 59°41° Dec

Precipitation by month inches

0″1″2″3″4″January: 3.46 in precipitation 3.5 JanFebruary: 3.57 in precipitation 3.6 FebMarch: 2.57 in precipitation 2.6 MarApril: 1.23 in precipitation 1.2 AprMay: 0.61 in precipitation 0.6 MayJune: 0.12 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: 0.68 in precipitation 0.7 OctNovember: 1.87 in precipitation 1.9 NovDecember: 3.55 in precipitation 3.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Concord Wwtp, CA (2 mi away); precipitation: Concord Wwtp, CA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9b.

945979b
Walnut Creek, CA · 3 mi
945189b
Concord, CA · 3 mi
945229b
Concord, CA · 3 mi
945249b
Concord, CA · 3 mi
945299b
Concord, CA · 3 mi
945209b
Concord, CA · 3 mi
945199b
Concord, CA · 4 mi
945989b
Walnut Creek, CA · 4 mi

California planting zones →

Questions about 94523

What planting zone is ZIP code 94523?

ZIP code 94523 (Pleasant Hill, 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 94523 get?

About 17.7 inches of precipitation a year (NOAA 1991–2020 normals, Concord Wwtp station).

How hot do summers get in Pleasant Hill, CA?

The average high peaks at 88 °F in July, with about 47 days a year at 90 °F or more.

What kind of soil does 94523 have?

The USDA soil survey maps Conejo at the center of ZIP 94523: clay loam, well drained, pH about 6.8 (neutral).

Did spring come early in Pleasant Hill, CA in 2026?

Spring leaf-out near 94523 came on Jan 30 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 Pleasant Hill, CA?

Intermediate onions: the longest day near 94523 is 14 h 48 min, so day-neutral types bulb best; long-day varieties may not bulb fully.