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

Planting zone for 94527 — Concord, CA

ZIP code 94527 (Concord, Contra Costa County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is March 8 and the first fall frost December 22.

Where ZIP 94527 is

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 frostMar 8
First frostDec 22
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 Concord, 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 Concord, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 8median — 50% chance of a later frost
Safe for tender plantsApril 15only 10% chance of frost after
First fall frostDecember 22median — 10% chance by Nov 23
Growing season282 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 8 and returns around January 16.

From the NOAA station Mt Diablo Junction, CA — 6 miles away, elevation 2,169 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 94527

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 25 – Feb 8
SpinachSow outdoors · Jan 25 – Feb 15
Broccoli, cabbageStart indoors · Dec 28 – Jan 11
Broccoli, cabbageTransplant · Feb 15 – Mar 1
Onion setsPlant outdoors · Feb 8 – Feb 22
PotatoesPlant outdoors · Feb 15 – Mar 1
LettuceSow outdoors · Feb 8 – Feb 22
Carrots, beetsSow outdoors · Feb 15 – Mar 1
TomatoesStart indoors · Jan 11 – Jan 25
TomatoesTransplant · Mar 15 – Mar 29
Peppers, eggplantStart indoors · Dec 28 – Jan 11
Peppers, eggplantTransplant · Mar 22 – Apr 5
BeansSow outdoors · Mar 15 – Mar 29
Sweet cornSow outdoors · Mar 15 – Mar 29
Cucumbers, squashSow outdoors · Mar 15 – Mar 29
Fall lettuce, spinachSow outdoors · Oct 27 – Nov 10
GarlicPlant cloves · Dec 8 – Jan 12
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 8) and first fall frost (Dec 22) 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 94527 came on Jan 30 — about the same time as the 1991–2020 average (Jan 31).

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 Concord, CA

The soil mapped at the center of ZIP 94527 is Los Robles — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH7.0neutral; 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: Los Robles clay loam.

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 94527; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Concord, CA

Summer high83 °Faverage high, July
Winter low41 °Faverage low, December
Hot days27days a year at 90 °F or more
Freezing nights19nights a year at 32 °F or less
Growing degree days3,645base 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
Precipitation19.1 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 54 °F, low 42 °F 54°42° JanFebruary: average high 55 °F, low 42 °F 55°42° FebMarch: average high 58 °F, low 43 °F 58°43° MarApril: average high 62 °F, low 44 °F 62°44° AprMay: average high 68 °F, low 49 °F 68°49° MayJune: average high 76 °F, low 55 °F 76°55° JunJuly: average high 83 °F, low 62 °F 83°62° JulAugust: average high 83 °F, low 61 °F 83°61° AugSeptember: average high 80 °F, low 60 °F 80°60° SepOctober: average high 72 °F, low 54 °F 72°54° OctNovember: average high 60 °F, low 46 °F 60°46° NovDecember: average high 53 °F, low 41 °F 53°41° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.70 in precipitation 3.7 JanFebruary: 4.09 in precipitation 4.1 FebMarch: 2.75 in precipitation 2.8 MarApril: 1.38 in precipitation 1.4 AprMay: 0.65 in precipitation 0.7 MayJune: 0.21 in precipitation 0.2 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.06 in precipitation 0.1 AugSeptember: 0.09 in precipitation 0.1 SepOctober: 0.90 in precipitation 0.9 OctNovember: 1.81 in precipitation 1.8 NovDecember: 3.46 in precipitation 3.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mt Diablo Junction, CA (6 mi away); precipitation: Concord 2.1 Se, CA (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9b.

945219b
Concord, CA · <1 mi
945189b
Concord, CA · 4 mi
945199b
Concord, CA · 4 mi
945989b
Walnut Creek, CA · 4 mi
945659b
Pittsburg, CA · 4 mi
945229b
Concord, CA · 4 mi
945249b
Concord, CA · 4 mi
945299b
Concord, CA · 4 mi

All 8 ZIP codes in Concord → · California planting zones →

Questions about 94527

What planting zone is ZIP code 94527?

ZIP code 94527 (Concord, 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).

When is the last frost in Concord, CA?

The median last spring frost (32 °F) near 94527 is March 8; after April 15 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mt Diablo Junction station.

When is the first frost in Concord, CA?

The median first fall frost near 94527 is December 22, giving a median frost-free growing season of 282 days.

When should I plant tomatoes in 94527?

Start tomato seeds indoors around Jan 11 – Jan 25 and set transplants outside around Mar 15 – Mar 29, one to three weeks after the median last frost.

How much rain and snow does 94527 get?

About 19.1 inches of precipitation a year (NOAA 1991–2020 normals, Concord 2.1 Se station).

How hot do summers get in Concord, CA?

The average high peaks at 83 °F in July, with about 27 days a year at 90 °F or more.

What kind of soil does 94527 have?

The USDA soil survey maps Los Robles at the center of ZIP 94527: clay loam, well drained, pH about 7.0 (neutral).

Did spring come early in Concord, CA in 2026?

Spring leaf-out near 94527 came on Jan 30 in 2026, about the same as the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Concord, CA?

Intermediate onions: the longest day near 94527 is 14 h 48 min, so day-neutral types bulb best; long-day varieties may not bulb fully.