What planting zone is Hayward, CA?

Hayward is in USDA plant hardiness zone 9b (average annual extreme minimum temperature 25 to 30°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Hayward?

In Hayward, CA the warmest month is September (avg high 78.3°F) and the coldest is December (avg low 42.5°F). It averages about 15.9″ of precipitation a year.

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Hayward, CA Planting Calendar & Frost Dates

USDA hardiness zone 9b · ZIP 94542 · elevation 12′ · NOAA & USDA data

Hayward sits in USDA zone 9b and is effectively frost-free — you can grow something outdoors year-round. The warmest month is September (avg high 78.3°F) and the coolest is December (avg low 42.5°F). Time plantings by the hot vs. cool season rather than by frost: grow heat-loving crops through the warm months and cool-season greens in the mild winter. The wettest month is February (3.2″).

Hardiness zone

min temp 25 to 30°F

Frost

Frost-free

grow year-round

Warmest month

September

avg high 78.3°F

Month-by-month typical weather in Hayward

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Fremont, CA (7.8 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)
January	58.6	42.6	50.6	3
February	61.4	44.4	52.9	3.2
March	65.1	46.4	55.8	2.5
April	67.7	48.3	58	1.2
May	71.1	51.9	61.5	0.5
June	75.3	54.7	65	0.2
July	77.9	56.8	67.3	0
August	78.2	57.1	67.7	0
September	78.3	56	67.2	0.1
October	73.3	52	62.6	0.7
November	64.6	46.2	55.4	1.6
December	58.4	42.5	50.5	3

What to plant when in Hayward

Hayward is frost-free, so there's no last-frost date to time from. Grow cool-season crops (lettuce, peas, broccoli, carrots) in the cooler months and warm-season crops (tomatoes, peppers, beans, squash) through the warm season.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in California

Union City, CA Fremont, CA San Leandro, CA Dublin, CA San Ramon, CA Pleasanton, CA Newark, CA Danville, CA

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Hayward Air Terminal, CA, 4.9 mi (confidence: high). Monthly weather normals: Fremont, CA, 7.8 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.