California Code, Business and Professions Code - BPC § 5442.5

(a) Directional and official signs and notices, including, but not be limited to, signs and notices pertaining to natural wonders or scenic and historical attractions that are otherwise required or authorized by law and conform to regulations adopted by the department.

(b) Signs, displays, and devices advertising the sale or lease of real property upon which they are located.

(c) Signs, displays, and devices, including, but not limited to, those that may be changed at reasonable intervals by electronic process or by remote control, advertising activities conducted on the property on which they are located.

(d) Signs lawfully in existence on October 22, 1965, as determined by the department to be landmark signs, including signs on farm structures or natural surfaces, or of historic or artistic significance the preservation of which, in the opinion of the department, would be consistent with the purposes of this section, as determined by regulations adopted by the department.

(e) Signs, displays, and devices advertising the distribution by nonprofit organizations of free coffee to individuals traveling on the interstate system or the primary system.  For the purpose of this subdivision, the term “free coffee” means, coffee for which a donation may be made, but is not required.