San Francisco Weather in August

San Francisco's dry summer weather along with moderate temperatures continue throughout August.

This page gives detailed information on the typical August temperature, precipitation, sun, humidity, wind and storms for San Francisco, California.

The temperature, rainfall, sunshine and wind speed numbers here are historical averages based on climate data gathered in downtown San Francisco near the corner of Buchanan and Hermann Streets. The rest of the measurements are averages at the San Francisco International Airport, located south of the city center.

Temperature Weather iconTemperature

68 °F August average high 20 °C
55 °F August average low 13 °C

In most years, San Francisco averages a daily maximum temperature for August that's between 66 and 70 degrees Fahrenheit (19 to 21 degrees Celsius). The minimum temperature usually falls between 54 and 56 °F (12 to 14 °C).

The days at San Francisco heat up most rapidly during August. By the end of the month, the temperature has climbed around 3 °F (2 °C) above what it was at the start.

10 days 70 °F max. or more (21 °C)
30 days 60 °F min. or less (16 °C)

Nearly every day in August warms to over 60 °F (16 °C) in San Francisco. The city averages 2 days this month when the thermometer reaches into the 80s °F (over 27 °C). Temperatures of 90 °F (32 °C) or above occur only rarely during August.

The thermometer normally dips to 60 °F (16 °C) or below every every night this month. But only about once a decade does August get as cool as 50 °F (10 °C).

Rainy Weather iconRain

0.1 in total precipitation 2 mm
1 day of rain

Most years, San Francisco gets no precipitation at all in August. About one in four years receives just 0.1 inches (1 mm) or so of rain for the month.

Sunny Weather iconSun

65 % sunshine
19 days clear skies

The sun's rays reach the ground in San Francisco during 65 percent of daylight hours on average in August, for a total of 273 hours in the month. Typically on 19 days this month the sky is mainly clear, with at most 30 percent cloud cover.

Sunlight in August at San Francisco lasts for 13 hours and 33 minutes a day on average. The longest day of the month is the 1st with 14 hours and 4 minutes of daylight. By the end of the month, the days have shortened to 13:01 from sunrise to sunset. These durations can vary by a minute or two from year to year.

Humid Weather iconHumidity

75 % August average humidity

The relative humidity in San Francisco during August usually peaks at 86 percent in the morning then drops to 57 percent by early afternoon.

Local Time1 am4 am7 am10 am1 pm4 pm7 pm10 pm
Humidity % 85 86 83 67 57 61 76 82

Windy Weather iconWind

10.5 mph August wind speed average 16.9 kph

August is a little windier than most other months in San Francisco.

Stormy Weather iconStorms

0 days rainfall of 0.5 inches (13 mm) or more
0 days with thunderstorms in August

Heavy rainstorms normally don't occur in San Francisco during August. About once in five years, an August thunderstorm passes through the city.


These weather data are long-term historical averages provided by the National Climatic Data Center of the United States. The temperature and precipitation numbers are 1981-2010 normals while the humidity and thunderstorm statistics are 1961-1990 normals.

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