Places like San Francisco's City Hall and The Bay Lights, the light sculpture on the Bay Bridge, will turn out the lights from 8:30 p.m. to 9:30 p.m. to raise awareness about the environmental impact humans have on the planet.
Earth Hour has become the world's largest voluntary environmental action, and San Francisco is the U.S. capital city for the event.
It was selected from 29 cities participating in the World Wildlife Foundation's Earth Hour challenge.
The city was awarded a $30,000 grant to promote renewable energy.
