Vallejo, California Weather
Coastal fog thickens at dawn. Day 77 of spring. Read this microseason across nine climate regions →
Vallejo weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——82°54°—
- FridayJun 5Overcast——88°56°+6°
- SaturdayJun 6Overcast——77°55°-11°
- SundayJun 7Overcast——74°54°-3°
- MondayJun 8Heavy Drizzle18%0.28″59°55°-15°
- TuesdayJun 9Drizzle18%0.03″68°55°+9°
- WednesdayJun 10Clear——76°55°+8°
PM2.5/PM10 ratio 0.69 with 8 mph wind — characteristic of long-range haze transport rather than a local source. AQI up 5 over the last 6 hours (gradual rise).
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 — peak already passed at 1 PM under clear skies. Levels should ease through evening.
- Present
- AQI 39
- UV peak
- 7.0 at earlier today
- Sky at peak
- clear
- Projected peak
- AQI 39
PM × Wind × Precip
PM2.5/PM10 ratio 0.69 with 8 mph wind — characteristic of long-range haze transport rather than a local source.
- PM2.5/PM10
- 0.69
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- transport
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
- 4:22 PM
- In sign
- ♒︎ Aquarius
Coastal fog thickens at dawn
Vallejo at a glance
- Today vs. normal: 3°F above the seasonal normal for this latitude
- Last frost: April 5 (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
September brings Vallejo's warmest temperatures (~71°F mean) while January delivers the coldest (~50°F). December sees peak rainfall at 4.5 inches, and July remains completely dry at 0.0 inches.
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 50° | 4.5″ | 15 |
| February | 54° | 3.6″ | 12 |
| March | 57° | 3.2″ | 11 |
| April | 60° | 1.4″ | 5 |
| May | 65° | 0.8″ | 3 |
| June | 69° | 0.2″ | 1 |
| July | 71° | 0.0″ | 1 |
| August | 71° | 0.0″ | 1 |
| September | 71° | 0.1″ | 1 |
| October | 66° | 1.0″ | 3 |
| November | 56° | 2.2″ | 7 |
| December | 50° | 4.5″ | 15 |
Regional context
Vallejo belongs to a hot-summer Mediterranean climate region — sharing similar temperature ranges, seasonal patterns, and growing conditions with nearby cities in this climate zone.
Similar climates: Los Angeles, CA, San Francisco, CA, San Diego, CA, Riverside, CA, Sacramento, CA.
Naturalist notes
Oak trees begin dropping their pollen in late April, coating surfaces with yellow dust as the trees complete their spring reproductive cycle.
Anna's hummingbirds start their courtship displays in late February, with males performing dramatic dive displays that produce distinctive whistling sounds.
Frequently asked
- When does it freeze in Vallejo?
- Vallejo's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Vallejo?
- December receives the most rainfall with about 4.5 inches on average; the city gets roughly 21 inches annually.
- What is the warmest month in Vallejo?
- September typically brings the warmest weather, averaging about 71°F.
- What is the coldest month in Vallejo?
- January typically brings the coldest weather, averaging about 50°F.
- When can I start a vegetable garden in Vallejo?
- Cool-season crops (peas, lettuce) can be planted around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) should wait until 1–2 weeks after.
- How many rainy days does Vallejo get?
- Vallejo averages about 75 rainy days per year.
- What hardiness zone is Vallejo?
- Vallejo's USDA hardiness zone depends on its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Vallejo, California experiences a hot-summer Mediterranean climate zone. January temperatures hover near 50°F while July averages 71°F — a 21°F seasonal swing.
Throughout the year, Vallejo receives about 21 inches of precipitation spread over roughly 75 rainy days.
Geographic factors shape the local weather patterns: latitude (38.1°N), proximity to large water bodies, and elevation determine what grows here, when frost occurs, and the daily weather conditions.