Sunnyvale, California Weather
Coastal fog thickens at dawn. Day 78 of spring. Read this microseason across nine climate regions →
Sunnyvale weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Foggy——77°55°—
- FridayJun 5Overcast——88°55°+11°
- SaturdayJun 6Overcast——77°53°-11°
- SundayJun 7Overcast——77°52°0°
- MondayJun 8Light Drizzle—0.02″67°56°-10°
- TuesdayJun 9Light Drizzle17%0.01″70°57°+3°
- WednesdayJun 10Clear——84°56°+14°
AQI 42 (Good), driven by PM2.5. AQI up 10 over the last 6 hours (gradual rise). PM2.5/PM10 ratio 0.69 with 8 mph wind — characteristic of long-range haze transport rather than a local source.
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 40 now. With UV 0.2 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 10 by mid-afternoon.
- Present
- AQI 40
- UV peak
- 0.2 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 10
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).
The higher the clouds, the finer the weather.
- Moonrise
- 7:04 AM
- Moonset
- 5:26 PM
- In sign
- ♒︎ Aquarius
Coastal fog thickens at dawn
Sunnyvale at a glance
- Today vs. normal: 14°F below the seasonal normal for this latitude
- Last frost: March 31 (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
August marks Sunnyvale's peak warmth with average temperatures around 68°F, while December brings the year's coldest conditions at roughly 51°F. Rain follows a Mediterranean pattern, with February delivering the heaviest precipitation at 3.2 inches and July remaining completely dry at 0.0 inches.
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 51° | 3.0″ | 6 |
| February | 53° | 3.2″ | 7 |
| March | 56° | 2.5″ | 6 |
| April | 58° | 1.2″ | 4 |
| May | 62° | 0.5″ | 2 |
| June | 65° | 0.2″ | 0 |
| July | 67° | 0.0″ | 0 |
| August | 68° | 0.0″ | 0 |
| September | 67° | 0.1″ | 0 |
| October | 63° | 0.7″ | 2 |
| November | 55° | 1.6″ | 4 |
| December | 51° | 3.0″ | 7 |
Regional context
Sunnyvale falls within the broader hot-summer Mediterranean climate zone, sharing temperature ranges and seasonal rhythms with surrounding communities. Cities throughout this region experience similar growing conditions and weather patterns.
Similar climates: Los Angeles, CA, San Francisco, CA, San Diego, CA, Riverside, CA, Sacramento, CA.
Naturalist notes
During late May, California poppies reach their peak bloom across local hillsides and open spaces.
Anna's hummingbirds begin their second nesting cycle around mid-May, taking advantage of the warming temperatures.
Frequently asked
- When does it freeze in Sunnyvale?
- Spring's final frost usually occurs around mid-April in Sunnyvale, while the first fall frost returns around mid-November.
- What is the rainy season in Sunnyvale?
- February brings the heaviest rainfall, averaging 3.2 inches, while the city's total annual precipitation reaches approximately 16 inches.
- What is the warmest month in Sunnyvale?
- August typically records the year's highest temperatures, with averages near 68°F.
- What is the coldest month in Sunnyvale?
- December sees the coolest temperatures, averaging around 51°F.
- When can I start a vegetable garden in Sunnyvale?
- Cool-season vegetables like peas and lettuce can be planted around the last spring frost in mid-April, while heat-loving crops such as tomatoes and peppers should wait 1–2 weeks later.
- How many rainy days does Sunnyvale get?
- Sunnyvale experiences rain on approximately 37 days each year.
- What hardiness zone is Sunnyvale?
- Sunnyvale's USDA hardiness zone depends on average minimum winter temperatures; consult the USDA's online zone finder using the city's ZIP code for current designation.
Climate
Sunnyvale, California experiences a hot-summer Mediterranean climate. Winter temperatures in January typically hover near 51°F, while July averages reach 67°F, creating a moderate 17°F seasonal swing.
Annual precipitation totals approximately 16 inches, distributed across roughly 37 rainy days throughout the year.
Local weather patterns respond to the city's latitude of 37.4°N, along with nearby water bodies and elevation. These factors determine growing seasons, frost timing, and daily weather variations.