Really the best way to gauge how busy it will be is to check the single day ticket price, if the ticket price for the day is $97 (a value day ticket ) it probably won't be too bad. There really isn't such a thing as a slow day at Disneyland, generally speaking school days are a lot slower than weekends.
WE ARE KINDA... SOMEWHAT... VERY... BUSY TODAY & WE ARE GUNNA BE KINDA... SOMEWHAT... VERY... BUSY TOMORROW... AND... AS I CHECKED MY "BUSY LOG" FROM YESTERDAY...WE WERE ALSO KINDA... SOMEWHAT... VERY... BUSY YESTERDAY. (I HOPE THIS ANSWERS YOUR QUESTION)
I'm not a worker of Disneyland but they're always busy, if you want to do Disneyland and California adventure right then you should get a fast pass. They're like ten dollars and you get to basically set up an appointment for the ride you want to go on and you also get your pictures for free
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