Fairfield, California Weather
Ceanothus blooms again. Day 93 of summer. Read this microseason across nine climate regions →
Fairfield weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 7:24 AM PDT · Open-Meteo
- TodaySep 21Clear later——75°57°—
- TuesdaySep 22Mostly Clear——81°56°+6°
- WednesdaySep 23Mostly Clear——94°56°+13°
- ThursdaySep 24Overcast——84°58°-10°
- FridaySep 25Overcast——83°58°-1°
- SaturdaySep 26Overcast——80°55°-3°
- SundaySep 27Overcast——81°55°+1°
Air quality now AQI 50 · Good
AQI 50 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 10.2 µg/m³, PM10 at 13.1 µg/m³ — typical background levels with no transport signature.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
PM × Wind × Precip
PM2.5 at 10.2 µg/m³, PM10 at 13.1 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.78
- Wind
- breezy
- 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).
September dries up ditches or breaks down bridges.
- Moonrise
- 4:39 PM
- Moonset
- 1:40 AM
- In sign
- ♑︎ Capricorn
Ceanothus blooms again
Read this microseason across nine climate regions →
All 72 microseasons on the year wheel →
Fairfield at a glance
- Today vs. normal: Today averages 66°F (high 75°F, low 57°F), 4°F below the 70°F normal for Sep 21
- Last frost: January 15 (1991–2020 median, NOAA station 3 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant tomatoes, peppers, beans, squash, fall brassicas, carrots; harvest tomatoes, peppers, beans, summer squash, winter squash
16-Day Forecast — Fairfield
- Mon75°57°1%
- Tue81°56°1%
- Wed94°56°0%
- Thu84°58°0%
- Fri83°58°0%
- Sat80°55°0%
- Sun81°55°1%
- Mon91°55°1%
- Tue98°60°1%
- Wed100°63°3%
- Thu90°67°1%
- Fri95°76°7%
- Sat103°71°0%
- Sun93°63°0%
- Mon88°54°0%
- Tue84°55°0%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Fairfield
Interactive wind and temperature map centered on Fairfield — it loads in your browser. Open the full weather map.
Right now in the garden
Peak growing season
As of September 21, the growing season is at its peak — the first frost (around December 14) is weeks away. Fall transplants go in about 10–12 weeks before the first frost, September 21 to October 5 here. This city's planting calendar for September: plant tomatoes, peppers, beans, squash, fall brassicas, and carrots; harvest tomatoes, peppers, beans, summer squash, and winter squash.
Sun & seasons in Fairfield
Fairfield sits in Solano County, where the year’s longest day runs 14h 50m of daylight and its shortest just 9h 30m — a swing of +5h 20m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Los Angeles, the state’s largest city, lies about 350 miles to the SE. The nearest town Fairfield tracks is Vallejo, roughly 15 miles to the SW.
Air quality in Fairfield
Air quality in Fairfield’s county has trended cleaner since 2020; its cleanest year on record was 2025 (median AQI 33). See the full air-quality history for Fairfield.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | lettuce, peas, spinach, radishes | radishes, fall brassicas, carrots |
| February | — | lettuce, peas, spinach, radishes |
| March | — | lettuce, peas, spinach, radishes |
| April | tomatoes, peppers, beans, squash | lettuce, peas |
| May | tomatoes, peppers, beans, squash | garlic |
| June | beans, squash | beans, summer squash |
| July | beans, squash | tomatoes, peppers, beans, summer squash |
| August | tomatoes, peppers, beans, squash | tomatoes, peppers, beans, summer squash, winter squash |
| September | tomatoes, peppers, beans, squash, fall brassicas, carrots | tomatoes, peppers, beans, summer squash, winter squash |
| October | — | tomatoes, peppers, beans, summer squash, winter squash |
| November | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash |
| December | lettuce, peas, spinach, radishes | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
A year in weather
In Fairfield, July runs warmest near 74°F and December coldest around 48°F, while December is the wettest month (5.4 inches) and July the driest (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
Similar climates Suisun City, CA, Green Valley, CA, Vacaville, CA
In Fairfield, NOAA NCEI 1991-2020 normals put January near 49°F and July near 74°F — a 25°F seasonal arc — with about 24.5 inches of precipitation over 42 rainy or snowy days.
Fairfield's moisture rides winter storm tracks: December brings 5.4 inches over 7.7 wet days, while July sees only 0.0 inches across 0.0 days in the dry warm season. That cool-season-wet pattern aligns Fairfield with places like Suisun City, CA, Green Valley, CA and Vacaville, CA.
Once Fairfield passes January 15, freezes fade and Fairfield's beds take lettuce, chard, arugula, and mustard greens. Tomatoes and peppers do best set out two weeks later in Fairfield, once nights clear the mid-40s°F. Frost returns to Fairfield near December 14, ending the tender-crop season. Open lawns in Fairfield whiten first when frost returns.
Similar climates: Suisun City, CA, Green Valley, CA, Vacaville, CA, Elmira, CA, Hartley, CA.
Frequently asked
- When does it freeze in Fairfield?
- In Fairfield, expect the last spring frost near January 15; Fairfield's first autumn frost comes around December 14.
- What is the rainy season in Fairfield?
- December is the wettest month in Fairfield, about 5.4 inches on average; the year totals roughly 25 inches.
- What is the warmest month in Fairfield?
- The warmest stretch in Fairfield comes in July, around 74°F on average.
- What is the coldest month in Fairfield?
- On average December is the chilliest month in Fairfield, about 48°F.
- When can I start a vegetable garden in Fairfield?
- Frost-hardy sowings begin at January 15 in Fairfield; warm-season starts follow two weeks on.
- How many rainy days does Fairfield get?
- Fairfield records around 42 days of measurable precipitation annually.
- What hardiness zone is Fairfield?
- Fairfield sits in the USDA zone set by December lows near 48°F; the USDA ZIP tool gives the band.
- What is the 10-day forecast for Fairfield?
- Fairfield's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in Fairfield?
- See this week's day-by-day rain chances for Fairfield in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Fairfield?
- Current conditions for Fairfield and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Fairfield forecast updated?
- The Fairfield forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Fairfield?
- Today's sunrise and sunset times for Fairfield are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for Fairfield?
- The next few days in Fairfield's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Fairfield sits at 38.3°N; its climate zone is hot-summer Mediterranean (Köppen approximation).
ZIP codes in Fairfield
- 94533
- 94534
- 94535