August Weather in Foster City, United States

Last updated: June 24, 2025

In August, the average temperature in Foster City, United States is a pleasant 18°C (65°F). Expect some variability, with minimum temperatures dropping to 12°C (54°F) and maximums soaring to 35°C (96°F). Enjoy clear skies, as precipitation is a mere 0 mm (0.0 in) over the entire month, and the average humidity remains comfortable at 54%.

August Temperature in Foster City

In August in Foster City, the average temperature is 18°C (65°F). Maximum temperatures can reach 35°C (96°F), while minimums can drop to 12°C (54°F). Overall, it's a great time to visit for those who enjoy mild weather with warm days and cooler evenings.

August Weather in Foster City: Daily Temperature Highs, Lows, and Averages

The chart illustrates August temperature patterns in Foster City, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Foster City, August typically has an average temperature of 18°C (65°F), with highs reaching up to 35°C (96°F) and lows dropping to around 12°C (54°F).

Data source: Temperature data for Foster City generated using information from the Copernicus Climate Change Service.

August Precipitation in Foster City

In Foster City in August, the precipitation amount is 0 mm (0.0 in) during 0 days.

August Precipitation Trends in Foster City

The chart displays monthly precipitation patterns in Foster City, with values for each month alongside August’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how August’s conditions compare to those of other months. In Foster City, August typically receives around 0 mm (0.0 inches) of precipitation spread over approximately 0 days.

Data source: Precipitation data for August generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

August Humidity in Foster City

In Foster City in August, humidity is 54%. With an average temperature of 18°C (65°F), this humidity feels like a light, refreshing breeze, making it comfortable for traveling and exploring the area without the discomfort of excessive stickiness.

August Average Humidity in Foster City

This chart illustrates the average monthly humidity levels in Foster City, with August’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In August, average humidity in Foster City is approximately 54%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for August generated using information from the Copernicus Climate Change Service.

August UV Index in Foster City

In Foster City in August, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Foster City.

Maximum UV Index Levels in Foster City for August

The chart shows the monthly maximum UV Index (UVI) for Foster City in August, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In August, the maximum UV index in Foster City typically reaches 10, which falls under the very high exposure category.

Data source: Foster City August UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How August Weather in Foster City Compares to Other Months

Weather in Foster City varies notably across the year, with each month offering distinct climate conditions. This page compares August’s weather to other months in Foster City, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Foster City, showing how August’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	11°C (52°F)	105 mm (4.1 inches)	82%	moderate
February Weather	11°C (53°F)	100 mm (3.9 inches)	84%	moderate
March Weather	12°C (54°F)	86 mm (3.4 inches)	82%	very high
April Weather	13°C (57°F)	33 mm (1.3 inches)	78%	very high
May Weather	15°C (59°F)	24 mm (0.9 inches)	71%	very high
June Weather	17°C (63°F)	2 mm (0.1 inches)	64%	extreme
July Weather	17°C (63°F)	0 mm (0.0 inches)	58%	extreme
August Weather	18°C (65°F)	0 mm (0.0 inches)	54%	very high
September Weather	18°C (66°F)	2 mm (0.1 inches)	55%	very high
October Weather	17°C (63°F)	24 mm (0.9 inches)	62%	high
November Weather	13°C (56°F)	47 mm (1.9 inches)	78%	moderate
December Weather	11°C (52°F)	88 mm (3.5 inches)	80%	moderate