Hey there, hi there, Mariel! Welcome to planDisney. I am so glad to hear that you are thinking about purchasing the California Resident Ticket Offer. I love when Disneyland Resort offers these specialty tickets for locals and it's so exciting this newest offer is extended to all California residents.
Unfortunately, you cannot upgrade one day of a multiday ticket to a
Park Hopper option. It will need to be every day of the ticket. However, I want to make sure you know that the cost is the same if you would upgrade a one-day ticket to a park hopper as it would be to upgrade a multi-day ticket. So it's actually a better deal to upgrade a multi-day ticket to a Park Hopper.
You can make the California Resident Ticket Offer a Park Hopper during the checkout process. You will also need to make
theme park ticket reservations for all of the days of the ticket during the checkout process. Don't worry if you do not know all of the dates in advance. You can just choose dates to check out and then you can go into your Disney account, cancel the reservations and then rebook for new dates once you figure them out.
If you are thinking about really maximizing your days in the parks, you can also look into
Disney Genie+. This is another upgrade to your ticket for a fee per ticket per day. You can also add this to all days of your ticket during your purchase or you can purchase it the day you want to use it once you have scanned your ticket into the park. I love using Disney Genie+ on days when my goal is to ride as many attractions as I can and really make the most of my day.
Mariel, thanks so much for stopping by with your question. I hope this helps you decide to upgrade your tickets to Park Hoppers! See you real soon!
Carrie