Weather in Sunnyvale, California
Fog and sun in daily rhythm. Day 59 of spring. Read this microseason across nine climate regions →
- TodayMay 16Mostly Clear—75°50°
- SundayMay 17Overcast—74°48°
- MondayMay 18Mostly Clear—83°57°
- TuesdayMay 19Clear—89°59°
- WednesdayMay 20Overcast—90°62°
- ThursdayMay 21Overcast—87°61°
- FridayMay 22Partly Cloudy—83°62°
- PM 2.5
- 7.7 μg/m³
- PM 10
- 12.0 μg/m³
- NO₂
- 1.3 μg/m³
- Ozone
- 92.0 μg/m³
- UV Index
- 2.3 Low
When the dew is on the grass, rain will never come to pass.
- Moonrise
- 1:11 PM
- Moonset
- 3:45 AM
- In sign
- ♉︎ Taurus
Fog and sun in daily rhythm
Sunnyvale at a glance
- Today vs. normal: 4°F below the seasonal normal for this latitude
- Last frost: March 31 (climatological average for this latitude)
- Microseason: 28 of 72, May 16–20
- Planting window: Direct sow okra, melons, and southern peas. Thin carrot rows.
Right now in the garden
Warm-season window is open
As of May 17, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
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.