People are correct about it being difficult to find free camping right on the coast. Now and again I see of a lower cost camp site. There is a beach or two in Washington state that has an area of hard enough sand to drive into and spend a night for free. But I have never heard of free 2 week places right by the ocean. They would of course be constantly mobbed with people if there was one.
Allmost all the free public lands for camping are at least several miles inland from the ocean. That is not going to be changing. The towns along the coast generally prohibit sleeping in vehicles overnight.
It is possible to be in comfortable temperatures in Arizona year around. You move into the northern mountain region for the summer months. But heads up about that scheme, it will rain most days during the monsoon season but the rain is generally only during the mid afternoon. Mornings are typically sunny. Rain at night sometimes happens but not every night. Of course you will also get a lot of rain along the Pacific coast except in Southern California.