Even though the First Amendment doesn’t give you any rights against your HOA, the Davis-Stirling Act does.
The Davis-Stirling Act provides that an HOA’s governing documents (for example, the CC&Rs, Bylaws, Rules and Regulations) can’t prohibit you from posting or displaying noncommercial signs, posters, flags, or banners on or inside your separate interest. (Civ. Code, § 4710(a).) What this means is that the HOA can’t stop you from posting signs, posters, flags, or banners, as long as your sign or banner doesn’t express a message that’s designed to advance a commercial interest, such as an ad for a business AND the sign is located on your separate portion of the property. (See Kasky v. Nike, Inc. (2002) 27 Cal.4th 939, 1271-72.) Which part of the property is your separate interest and which part is common area depends on the type of development you live in and your CC&Rs.
The provision does come with a few caveats.
The statute comes with a public health or safety provision which states that your sign cannot convey a message which threatens public health or safety, or violates a local, state, or federal law. (Civ. Code, § 4710(a).)
And although you’re free to display your sign, poster, flag, or banner on your yard, window, door, balcony or the property’s outside wall, you need to limit your political expression to the following mediums: paper, cardboard, cloth, plastic, or fabric. (Civ. Code, § 4710(b).)