Good point about appropriate gear. Although I carry about the same pieces of clothing for CA mountains and north coast, I take more wool items on the coast in moderate/damp conditions. On the coast I just accept being wet and have a dry layer for night and then put the wet stuff back on in the morning. I have a light weight wool zip-T that I can wring out and put on and it really is not bad. In the mountains, I really try to stay dry and take more down gear.

Another big thing about the coast is the wind. Not only check the temp and rain forecast, but look closely at the wind directions. You really need a wind shell on the coast. And tide tables! There are hikes on the coast where you have to hit the tides JUST right. Once I hiked 5 miles barefoot on the beach - cannot say I ever hiked barefoot in the mountains. I do not take wading shoes or camp shoes on the coast - just go barefoot.

I got a 4-oz down sweater last year and really love it. I always take it to the mountains "just in case" for cold mornings. I really do not "need" it most of the time, but for the little extra weight, it is a good piece of "insurance."

Be aware that there can easily be a 10-degree difference from the "forecast" depending on microclimates. Choosing a campsite is as important as extra clothing. When looking at the NWS forecast I poke around and see what the forecast is for various microclimates - click on a valley, then a mountainside, then in a forested area, then in a bare area, near a lake, etc. I think all those factors are built into their forecast models.