California's "Basic Speed Law" says:

Question

The "Basic Speed Law" means that you may never drive faster than would be safe in current conditions. For example, if you drive 45 mph in a 55 mph zone during a dense fog, even though you are below the posted limit, you may be cited for driving too fast for conditions.

Accepted Answer

You should never drive faster than is safe for current conditions.

Answer

You should never drive faster than posted speed limits.

Answer

The maximum speed limit in California is 70 mph on certain freeways.