Usually wet. Sometimes very wet.
And in areas hit by fires, there is a high risk of mud slides.
Slides often close sections of Highway 1 during the winter.

Climate data from Western Regional Climate Center -
Western Regional Climate Center

And, specifically, Morro Bay - for example -
Dec. Avg Hi - 62F; Avg Lo - 43F, Avg Precip - 2.66 in.

Wettest in Jan/Feb, but Dec & Mar almost as wet.