It is legal for the first 5 inches used as a visor

The California window tint law consists of only a sun visor strip of tint on up to 4 inches of the front windshield being legal, anything above 4 (or 5) inches is considered illegal. 

You can get a very light see through film to block out UV rays. 

If you desire to block out UV rays from your vehicle, then it is possible to associate yourself with the benefits of window tint and darkening tint to be protected against UV rays. To further elaborate, clear or tinted films assist with reducing the amount of UV radiation that penetrates the tempered glass by over 98 percent. Other sun reign window film tints will reject about 97 percent of the UV rays.

If you have a medical reason you can bypass

Although window tint has a large amount of beneficial outcomes, there are also its cons. While tint is accessible to reduce sun glare, the driver of the vehicle can have visibility issues, mostly during the night. Traffic will further be obstructed from the driver’s view if your vehicle has tinted windows. To add on, the California tint laws do not authorize specific colors of tint, such as blue tint colors, red, amber, and it is permitted that the side windows are achromatic. However, it is illicit to utilize a vehicle with a window tint that contains a visible light transmittance of less than 35 percent or minimizes the light transmittance on the front windshield by about below 70 percent. 

Windshield tint can be dangerous.

To play it safe, it is the finest option to keep your tint percentage at about 30 percent because it is the ideal balanced hue between protecting your privacy and having shade. Although, a shade above 50 percent is examined as clear.