You're never far from one of them. Deciding where to go might depend on when you'll be there. Only the inland, northern entries, such as Mendocino National Forest, are likely to be affected by winter snow. Of course, all the parks have a chance of being wet and dreary between November and February. Spring and autumn are always safe bets.
Summer takes more thought.
The coastal parks and state beaches are wonderful retreats from the heat, but some of the valley parks will put you right into the oven. Unless otherwise stated, parks are open year-round and 24 hours a day. Most regional parks have no admission charge. Pets are welcome in campgrounds and picnic areas but usually not on trails or beaches. With millions of jittery city folks visiting California's parks each year, the campgrounds are often filled to the brim, especially between Memorial Day and Labor Day.