Vallejo, California Weather
Ceanothus blooms again. Day 93 of summer. Read this microseason across nine climate regions →
Vallejo weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 7:23 AM PDT · Open-Meteo
- TodaySep 21Clear later——68°56°—
- TuesdaySep 22Overcast——75°56°+7°
- WednesdaySep 23Mostly Clear——83°56°+8°
- ThursdaySep 24Overcast——78°61°-5°
- FridaySep 25Overcast——76°61°-2°
- SaturdaySep 26Overcast——71°59°-5°
- SundaySep 27Overcast——75°58°+4°
Air quality now AQI 43 · Good
AQI 43 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 8.2 µg/m³, PM10 at 10.6 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 8.2 µg/m³, PM10 at 10.6 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.77
- 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).
September dries up ditches or breaks down bridges.
- Moonrise
- 4:39 PM
- Moonset
- 1:42 AM
- In sign
- ♑︎ Capricorn
Ceanothus blooms again
Read this microseason across nine climate regions →
All 72 microseasons on the year wheel →
Vallejo at a glance
- Today vs. normal: Today averages 62°F (high 68°F, low 56°F), 8°F below the 70°F normal for Sep 21
- Last frost: January 17 (1991–2020 median, NOAA station 4 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant tomatoes, peppers, beans, squash; harvest tomatoes, peppers, beans, summer squash, winter squash
16-Day Forecast — Vallejo
- Mon68°56°2%
- Tue75°56°1%
- Wed83°56°0%
- Thu78°61°0%
- Fri76°61°0%
- Sat71°59°0%
- Sun75°58°1%
- Mon81°59°1%
- Tue90°65°1%
- Wed93°67°4%
- Thu84°70°1%
- Fri93°75°6%
- Sat97°73°0%
- Sun83°64°0%
- Mon77°59°0%
- Tue75°60°0%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Vallejo
Interactive wind and temperature map centered on Vallejo — 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 27) is weeks away. Fall transplants go in about 10–12 weeks before the first frost, October 4 to October 18 here. This city's planting calendar for September: plant tomatoes, peppers, beans, and squash; harvest tomatoes, peppers, beans, summer squash, and winter squash.
Sun & seasons in Vallejo
Vallejo sits in Solano County, where the year’s longest day runs 14h 49m of daylight and its shortest just 9h 31m — a swing of +5h 18m 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 349 miles to the SE. The nearest town Vallejo tracks is Fairfield, roughly 15 miles to the NE.
Air quality in Vallejo
Air quality in Vallejo’s county has trended cleaner since 2020; its cleanest year on record was 2025 (median AQI 33). See the full air-quality history for Vallejo.
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, winter squash |
| August | beans, squash | tomatoes, peppers, beans, summer squash, winter squash |
| September | tomatoes, peppers, beans, squash | tomatoes, peppers, beans, summer squash, winter squash |
| October | beans, squash, fall brassicas, carrots | tomatoes, peppers, beans, summer squash, winter squash |
| November | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash |
| December | lettuce, peas, spinach, radishes, garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
A year in weather
In Vallejo, September runs warmest near 71°F and January coldest around 50°F, while December is the wettest month (4.5 inches) and July the driest (0.0 inches).
| Month | Mean temp | Precip |
|---|---|---|
| January | 50° | 4.5″ |
| February | 54° | 3.6″ |
| March | 57° | 3.2″ |
| April | 60° | 1.4″ |
| May | 65° | 0.8″ |
| June | 69° | 0.2″ |
| July | 71° | 0.0″ |
| August | 71° | 0.0″ |
| September | 71° | 0.1″ |
| October | 66° | 1.0″ |
| November | 56° | 2.2″ |
| December | 50° | 4.5″ |
Regional context
Similar climates Crockett, CA, American Canyon, CA, Benicia, CA
Vallejo's climate, from NOAA NCEI 1991-2020 station normals, pairs 50°F Januarys with 71°F Julys — a 21°F swing. About 21.5 inches of precipitation falls each year.
Cool-season fronts carry Vallejo's rain: December logs 4.5 inches, against July's 0.0 inches — winter does the heavy lifting in Vallejo. That groups Vallejo with places like Crockett, CA, American Canyon, CA and Benicia, CA on the same cool-season storm track.
Vallejo's growing window opens around January 17, once Vallejo's overnight lows stop freezing — sow lettuce, chard, arugula, and mustard greens. Hold Vallejo's tender crops — tomatoes, peppers, basil — until 10-14 days past Vallejo's last frost. Vallejo's window closes around December 27 as Vallejo's overnight lows return below freezing. In about half of years, Vallejo's last freeze comes after January 17.
Similar climates: Crockett, CA, American Canyon, CA, Benicia, CA, Rodeo, CA, Port Costa, CA.
Frequently asked
- When does it freeze in Vallejo?
- Frost typically leaves Vallejo by January 17 and returns to Vallejo near December 27.
- What is the rainy season in Vallejo?
- December is the wettest month in Vallejo, about 4.5 inches on average; the year totals roughly 21 inches.
- What is the warmest month in Vallejo?
- Vallejo peaks in September, when the mean runs near 71°F.
- What is the coldest month in Vallejo?
- January is Vallejo's coldest month, averaging about 50°F.
- When can I start a vegetable garden in Vallejo?
- Around January 17, start frost-hardy crops in Vallejo; tomatoes and basil belong a fortnight later.
- What hardiness zone is Vallejo?
- With January around 50°F, Vallejo's zone reflects that minimum — the USDA ZIP map confirms Vallejo's band.
- What is the 10-day forecast for Vallejo?
- Vallejo'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 Vallejo?
- See this week's day-by-day rain chances for Vallejo in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Vallejo?
- Current conditions for Vallejo and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Vallejo forecast updated?
- The Vallejo forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Vallejo?
- Today's sunrise and sunset times for Vallejo 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 Vallejo?
- The next few days in Vallejo's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Vallejo sits at 38.1°N; its climate zone is hot-summer Mediterranean (Köppen approximation).
ZIP codes in Vallejo
- 94589
- 94590
- 94591
- 94592