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 other measurements are averages at San Francisco International Airport, located south of the city center.
Temperature
| 68 °F | August average high | 20 °C |
| 56 °F | August average low | 13 °C |
| 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 degrees Celsius) 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 consistently drops into the 50s °F (below 16 °C) overnight this month. But it usually gets no cooler than 50 °F (10 °C).
Rain
| 0.1 in | total precipitation | 2 mm |
| 1 day | of rain |
Most years, San Francisco gets no precipitation at all in August.
Sun
| 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.
Humidity
| 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 Time | 1 am | 4 am | 7 am | 10 am | 1 pm | 4 pm | 7 pm | 10 pm |
| Humidity % | 85 | 86 | 83 | 67 | 57 | 61 | 76 | 82 |
Wind
| 10.5 mph | August wind speed average | 16.9 kph |
August is a little windier than most other months in San Francisco.
Storms
| 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.
Reference
The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals.