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

Planting zone for 94514 — Byron, CA

ZIP code 94514 (Byron, Contra Costa County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F.

Where ZIP 94514 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 Byron, 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 Tracy Pumping Plt, CA — 4 miles away, elevation 62 ft) the median growing season is 330 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 94514 came on Jan 31 — 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 Byron, CA

The soil mapped at the center of ZIP 94514 is Linne — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Linne clay loam, 5 to 15 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 94514; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Byron, CA

Summer high93 °Faverage high, July
Winter low40 °Faverage low, December
Hot days82days a year at 90 °F or more
Freezing nights10nights a year at 32 °F or less
Growing degree days5,166base 50 °F — the season’s usable heat
Longest day14 h 47 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
Precipitation12.4 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 41 °F 56°41° JanFebruary: average high 62 °F, low 44 °F 62°44° FebMarch: average high 67 °F, low 47 °F 67°47° MarApril: average high 73 °F, low 50 °F 73°50° AprMay: average high 80 °F, low 55 °F 80°55° MayJune: average high 88 °F, low 59 °F 88°59° JunJuly: average high 93 °F, low 62 °F 93°62° JulAugust: average high 93 °F, low 62 °F 93°62° AugSeptember: average high 89 °F, low 60 °F 89°60° SepOctober: average high 79 °F, low 55 °F 79°55° OctNovember: average high 66 °F, low 46 °F 66°46° NovDecember: average high 57 °F, low 40 °F 57°40° Dec

Precipitation by month inches

0″1″2″3″January: 2.51 in precipitation 2.5 JanFebruary: 2.32 in precipitation 2.3 FebMarch: 1.60 in precipitation 1.6 MarApril: 0.84 in precipitation 0.8 AprMay: 0.52 in precipitation 0.5 MayJune: 0.13 in precipitation 0.1 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.01 in precipitation 0.0 AugSeptember: 0.08 in precipitation 0.1 SepOctober: 0.67 in precipitation 0.7 OctNovember: 1.32 in precipitation 1.3 NovDecember: 2.37 in precipitation 2.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Tracy Pumping Plt, CA (4 mi away); precipitation: Tracy Pumping Plt, CA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9b.

953919b
Tracy, CA · 4 mi
945059b
Discovery Bay, CA · 4 mi
945139b
Brentwood, CA · 7 mi
945519b
Livermore, CA · 8 mi
945489b
Knightsen, CA · 10 mi
945319b
Antioch, CA · 12 mi
945619b
Oakley, CA · 12 mi
953779b
Tracy, CA · 12 mi

California planting zones →

Questions about 94514

What planting zone is ZIP code 94514?

ZIP code 94514 (Byron, 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 94514 get?

About 12.4 inches of precipitation a year (NOAA 1991–2020 normals, Tracy Pumping Plt station).

How hot do summers get in Byron, CA?

The average high peaks at 93 °F in July, with about 82 days a year at 90 °F or more.

What kind of soil does 94514 have?

The USDA soil survey maps Linne at the center of ZIP 94514: clay loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Byron, CA in 2026?

Spring leaf-out near 94514 came on Jan 31 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 Byron, CA?

Intermediate onions: the longest day near 94514 is 14 h 47 min, so day-neutral types bulb best; long-day varieties may not bulb fully.