Foster City (CA) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Foster City.
Climate overview of Foster City
The climate in Foster City, California, United States of America, sees a moderate range of temperatures across the year, from 24°C (75°F) in September down to 14°C (57°F) in December.
The city has a relatively dry climate, receiving around 401 mm (16 in) of rainfall per year. It does experience a distinct dry season from April to November. December is the wettest month and July the driest. May is the sunniest month, averaging 10.8 hours of sunshine per day.
Foster City Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Foster City - and find the best time to visit.
Monthly Temperature in Foster City
The climate in Foster City experiences moderate temperature changes, with mild shifts between seasons. On average, daytime temperatures range from a comfortable 24°C (75°F) in September to a moderate 14°C (57°F) in December.
Nighttime temperatures range from 14°C (57°F) in September to 6°C (43°F) in December.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Foster City
Foster City tends toward drier weather patterns, receiving approximately 401 mm (16 in) of rain per year. The seasons in Foster City bring significant changes in precipitation. The wettest month, December, receives moderate rainfall, with an average of 96 mm (3.8 in) of precipitation. This rainfall is distributed across 12 rainy days.
In contrast, the driest month, July, experiences much less rainfall, totaling 0 mm (0 in) over 0 rainy days. These distinct seasonal differences provide diverse experiences throughout the year. For more details, please visit our Foster City Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Sunshine Hours in Foster City
In Foster City, summer days are longer and more sunny, with daily sunshine hours peaking at 10.8 hours in May. As the darker season arrives, the brightness of the sun becomes less. December sees a soft sun for only 5.3 hours per average day.
Visit our detailed sunshine hours page for more information.
Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Water Temperature in Foster City
The mean water temperature over the year ranges from 12°C (54°F) in January to 14°C (57°F) in June.
Water temperature over the year
Humidity in Foster City by Month
The relative humidity is high throughout the year in Foster City.
The city experiences its highest humidity in January, reaching 80%. In June, the humidity drops to its lowest level at 71%. What does this mean? Read our detailed page on humidity levels for further details.
Relative humidity over the year
Wind Speed in Foster City
The mean wind speed over the year ranges from 3 m/s (6 knots) in January, November and December to 7 m/s (14 knots) in June and July. What does this mean?
The mean monthly wind speed over the year (meters per second)
Best Time to Visit Foster City
Each month is rated for comfortable sightseeing weather — mild temperatures and low rainfall. Tap a month for its full averages; your ideal time may differ for a beach or winter trip (see below).
- Best overall: May, June, July, August, September and October
- Warmest weather: June, July, August and September
- Most sunshine: April, May, June and July
- Fewest rainy days: June, July, August and September
- Climate seasons: a distinct dry season from April to November
Frequently asked questions about the climate in Foster City
What is the best time to visit Foster City?
May, June, July, August, September and October typically offer the most optimal weather in Foster City. In contrast, January, February and December tend to have less optimal conditions. Foster City has a distinct dry season from April to November.
What temperatures can I expect in Foster City?
Daytime highs range from 14°C (57°F) in December to 24°C (75°F) in September. Nighttime lows range from 6°C (43°F) to 14°C (57°F).
How much rain does Foster City get?
Annual rainfall is around 401 mm (16 in). December is the wettest month with 96 mm (3.8 in), while July is the driest with 0 mm (0 in).
How sunny is Foster City?
Foster City receives around 3,058 hours of sunshine per year. May is the sunniest month with 324 hours, while December is the cloudiest with just 160 hours. Overall, Foster City enjoys abundant sunshine.
Foster City 3-Day Forecast
Foster City (CA) 3-Day Forecast
Foster City on the map
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