Sunrise and sunset times are calculated using your city's exact coordinates (37.77493°, -122.41942°) and the astronomical horizon. Times shown are in America/Los_Angeles local time and automatically adjust for Daylight Saving Time when applicable.
Solar noon is when the sun reaches its highest point in the sky. This is not always exactly at 12:00 PM clock time due to the equation of time and your location within the time zone. The solar noon shown above is calculated precisely for San Francisco.
Day length is the total time between sunrise and sunset. It varies throughout the year due to Earth's axial tilt. Near the equator, day length stays relatively constant year-round. At higher latitudes, summer days are much longer than winter days.
Civil twilight begins when the sun is 6° below the horizon (before sunrise) and ends when it reaches 6° below after sunset. During civil twilight, there is enough light for most outdoor activities without artificial illumination.