https://www.dmv.ca.gov/portal/dmv/detail/pubs/hdbk/turns
Legal U-Turns
A U-turn is turning your vehicle around in the street to go back the way you came. To make a U-turn, signal and use the far left lane or the center left turn lane. You may make a legal U-turn:
- Across a double yellow line when it is safe and legal.
- In a residential district:
- If there are no vehicles approaching you within 200 feet.
- Whenever a traffic sign, light, or signal protects you from approaching vehicles.
- At an intersection on a green light or green arrow, unless a "No Uturn" sign is posted.
- On a divided highway, only if an opening is provided in the center divider.