Fairfield, California Weather
Coastal fog thickens at dawn. Day 77 of spring. Read this microseason across nine climate regions →
Fairfield weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——88°56°—
- FridayJun 5Overcast——92°59°+4°
- SaturdayJun 6Overcast——80°54°-12°
- SundayJun 7Overcast——78°49°-2°
- MondayJun 8Drizzle17%0.18″60°53°-18°
- TuesdayJun 9Light Drizzle—0.04″69°55°+9°
- WednesdayJun 10Clear——84°52°+15°
Ozone at AQI 39 now. AQI down 6 over the last 6 hours (steady decline since this morning). With UV 8.9 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 46 by mid-afternoon.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 39 now. With UV 8.9 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 46 by mid-afternoon.
- Present
- AQI 39
- UV peak
- 8.9 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 46
PM × Wind × Precip
PM2.5 at 5.1 µg/m³, PM10 at 6.5 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.78
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- background
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 6:35 AM
- Moonset
- 4:20 PM
- In sign
- ♒︎ Aquarius
Coastal fog thickens at dawn
Fairfield at a glance
- Today vs. normal: 76°F — typical for the season
- Last frost: April 6 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
July brings Fairfield's peak warmth with mean temperatures around 74°F, while December delivers the coldest conditions at roughly 48°F. Rain follows the opposite pattern — December brings the heaviest precipitation at 5.4 inches, while July typically sees 0.0 inches.
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 49° | 4.7″ | 8 |
| February | 52° | 5.0″ | 8 |
| March | 56° | 3.3″ | 7 |
| April | 60° | 1.5″ | 3 |
| May | 65° | 0.7″ | 2 |
| June | 71° | 0.2″ | 0 |
| July | 74° | 0.0″ | 0 |
| August | 74° | 0.0″ | 0 |
| September | 72° | 0.1″ | 0 |
| October | 65° | 1.1″ | 2 |
| November | 55° | 2.5″ | 5 |
| December | 48° | 5.4″ | 8 |
Regional context
As part of the hot-summer Mediterranean climate region, Fairfield shares temperature ranges, seasonal patterns, and growing conditions with other nearby cities in this climate zone.
Similar climates: Los Angeles, CA, San Francisco, CA, San Diego, CA, Riverside, CA, Sacramento, CA.
Naturalist notes
Late May brings the distinctive calls of Western Bluebirds as they establish territories in oak woodlands around Fairfield.
California poppies reach peak bloom across the region's grasslands during April and early May.
Frequently asked
- When does it freeze in Fairfield?
- Spring's final frost in Fairfield typically occurs around mid-April, while the first fall frost returns around mid-November.
- What is the rainy season in Fairfield?
- December stands as the wettest month, delivering about 5.4 inches of rain on average, contributing to the city's annual total of roughly 25 inches.
- What is the warmest month in Fairfield?
- July typically registers as the warmest month, with temperatures averaging about 74°F.
- What is the coldest month in Fairfield?
- December usually brings the coldest temperatures, averaging about 48°F.
- When can I start a vegetable garden in Fairfield?
- Cool-season crops like peas and lettuce can be planted around the last spring frost in mid-April, while warm-season crops such as tomatoes and peppers should wait 1–2 weeks after.
- How many rainy days does Fairfield get?
- Fairfield experiences about 42 rainy days per year on average.
- What hardiness zone is Fairfield?
- Fairfield's USDA hardiness zone depends on its lowest average winter temperature; the USDA's online lookup tool can provide the current zone designation using the city ZIP code.
Climate
Fairfield, California experiences a hot-summer Mediterranean climate. Winter temperatures in January hover near 49°F, while July brings averages of 74°F — creating a 25°F seasonal swing.
Annual precipitation totals about 25 inches, falling across roughly 42 rainy days throughout the year.
Geography shapes Fairfield's weather patterns through its latitude of 38.3°N, proximity to large water bodies, and elevation. These factors determine growing conditions, frost timing, and daily weather variations.