When is the last frost in Fairfield, CA?

The average last spring frost (50% probability of 32°F) in Fairfield is around January 15, based on NOAA/NCEI 1991–2020 normals at the Fairfield, CA station (3.5 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Fairfield?

The average first fall frost in Fairfield, CA is around December 14, giving roughly a 336-day frost-free growing season.

What planting zone is Fairfield, CA?

Fairfield 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 Fairfield?

In Fairfield, CA the warmest month is July (avg high 89.6°F) and the coldest is December (avg low 40.1°F). It averages about 24.5″ of precipitation a year.

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Fairfield, CA Planting Calendar & Frost Dates

USDA hardiness zone 9b · ZIP 94534 · elevation 12′ · NOAA & USDA data

Fairfield is in USDA hardiness zone 9b (winters can dip to 25 to 30°F), with a growing season of about 336 days between the average last spring frost (January 15) and first fall frost (December 14). The warmest month is July (avg high 89.6°F); the coldest is December (avg low 40.1°F). It averages 24.5″ of precipitation a year. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp 25 to 30°F

Last spring frost

January 15

avg (50% prob, 32°F)

First fall frost

December 14

avg (50% prob, 32°F)

Growing season

336 days

frost-free window

Warmest month

July

avg high 89.6°F

Month-by-month typical weather in Fairfield

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Fairfield, CA (3.5 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)
January	56.6	40.4	48.5	4.7
February	61.6	42.9	52.2	5
March	66.4	45.4	55.9	3.3
April	71.3	47.9	59.6	1.5
May	77.8	52.2	65	0.7
June	85.4	56.1	70.8	0.2
July	89.6	57.9	73.8	0
August	89.2	58	73.6	0
September	86.9	56.6	71.7	0.1
October	78.2	52.3	65.2	1.1
November	65.6	45.2	55.4	2.6
December	56.7	40.1	48.4	5.4

What to plant when in Fairfield

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: December 4 · Transplant out: January 22
Peppers	warm	Start seeds indoors: November 20 · Transplant out: January 29
Cucumbers	warm	Direct sow: January 22
Zucchini / squash	warm	Direct sow: January 22
Bush beans	warm	Direct sow: January 22
Sweet corn	warm	Direct sow: January 22
Basil	warm	Transplant out: January 22
Peas	cool	Sow (spring): December 11 · Sow (fall): October 19
Spinach	cool	Sow (spring): December 4 · Sow (fall): October 19
Lettuce	cool	Sow (spring): December 18 · Sow (fall): October 19
Kale	cool	Transplant (spring): December 25 · Sow (fall): October 5
Broccoli	cool	Transplant (spring): January 1
Carrots	cool	Sow (spring): December 25 · Sow (fall): October 5
Onions	cool	Transplant (spring): December 18
Potatoes	cool	Plant seed potatoes: January 1
Radishes	cool	Sow (spring): December 18 · Sow (fall): November 2

Dates are computed from Fairfield's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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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.

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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 — Fairfield, CA, 3.5 mi (confidence: high). Monthly weather normals: Fairfield, CA, 3.5 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.