Vacaville, California Weather
Coastal fog thickens at dawn. Day 78 of spring. Read this microseason across nine climate regions →
Vacaville weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Clear——91°60°—
- FridayJun 5Mostly Clear——95°65°+4°
- SaturdayJun 6Overcast——82°55°-13°
- SundayJun 7Overcast——82°49°0°
- MondayJun 8Drizzle19%0.12″61°48°-21°
- TuesdayJun 9Light Drizzle15%—79°57°+18°
- WednesdayJun 10Clear——93°56°+14°
Ozone at AQI 500 — peak already passed at 1 PM under clear skies. AQI up 25 in the last 6 hours — air quality is degrading. Levels should ease through evening.
AVOID OUTDOORS Avoid outdoor exertion. Keep windows closed; use HEPA filtration indoors if available.
What's driving it
Ozone × UV × Sky
Ozone at AQI 500 — peak already passed at 1 PM under clear skies. Levels should ease through evening.
- Present
- AQI 500
- UV peak
- 1.0 at earlier today
- Sky at peak
- clear
- Projected peak
- AQI 500
PM × Wind × Precip
PM2.5 at 6.5 µg/m³, PM10 at 8.7 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.75
- 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).
The higher the clouds, the finer the weather.
- Moonrise
- 7:06 AM
- Moonset
- 5:24 PM
- In sign
- ♒︎ Aquarius
Coastal fog thickens at dawn
Vacaville at a glance
- Today vs. normal: 10°F above the seasonal normal for this latitude
- 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 5, 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
Vacaville's warmest month is July, with a mean near 74°F, and its coldest is December, averaging about 48°F. Rainfall peaks in December at 5.4 inches and reaches its minimum in July at 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
Vacaville belongs to a hot-summer Mediterranean climate region, a group whose cities share comparable temperature ranges, seasonal patterns, and growing conditions.
Similar climates: Los Angeles, CA, San Francisco, CA, San Diego, CA, Riverside, CA, Sacramento, CA.
Naturalist notes
Western kingbirds return to the lower Sacramento Valley by mid-April, a reliable phenological marker as last frost exits the Vacaville area.
In late spring, the first brood of pipevine swallowtail butterflies appears on California Dutchman's pipe, coinciding with soil temperatures warm enough for warm-season vegetable starts.
Frequently asked
- When does it freeze in Vacaville?
- Vacaville's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Vacaville?
- December is the wettest month, averaging about 5.4 inches of rain; the city receives roughly 25 inches annually.
- What is the warmest month in Vacaville?
- July is typically the warmest month, averaging about 74°F.
- What is the coldest month in Vacaville?
- December is typically the coldest month, averaging about 48°F.
- When can I start a vegetable garden in Vacaville?
- Cool-season crops such as peas and lettuce can be sown around the last spring frost in mid-April; warm-season crops like tomatoes and peppers wait until one to two weeks after.
- How many rainy days does Vacaville get?
- Vacaville averages about 42 rainy days per year.
- What hardiness zone is Vacaville?
- Vacaville's USDA hardiness zone is set by its lowest average winter temperature; current zone designations can be checked via the USDA's online lookup using the city ZIP code.
Climate
Vacaville, California experiences a hot-summer Mediterranean climate. Mean January temperatures sit near 49°F while July averages 74°F, a seasonal swing of 25°F.
The city receives about 25 inches of precipitation spread across roughly 42 rainy days each year.
Latitude (38.4°N), distance to large water bodies, and local elevation together set the annual rhythm—shaping what grows here, when frost is likely, and the character of daily weather.