Hey there, Kathryn! Welcome to planDisney. We are so glad that you've dropped by with your question.
A character breakfast is a wonderful way to start your Disney day and
Storytellers Cafe is a great choice! The answer to your question is yes. You will be able to access Storytellers Cafe and then enter Disney California Adventure Park afterward. If you are walking or driving and parking at one of the Disneyland parking lots or areas, you can access
Disney's Grand Californian Hotel & Spa by heading to Downtown Disney District and using that entrance between Sephora and The Disney Dress Shop. Just follow the signs to head to Storytellers Cafe. When you are finished with breakfast you can then actually use the Disney's Grand Californian Hotel & Spa entrance into Disney California Adventure Park, this will have you entering the park just across from Grizzly River Run.
Halloween time will be happening when you are in the parks, so be sure to enjoy the attractions with overlays and take in all the decor. My favorite is Cars Land which transforms into Radiator Screams. Be sure to check it out both during the day and again at night!
Kathryn, thanks so much for your question. Please come back and see us again with any other questions you might have.
Carrie