Ahoy, Maria!
Congratulations on booking your Disney Cruise, and that's exciting that you'll be celebrating your princess' birthday while you're on board!
You'll definitely want to note your daughter's birthday under Special Requests when you go to the Customize Your Cruise Page under the
DisneyCruise.com Planning Center. Then, when you're onboard, you can go by Guest Services or to your head server and remind them of when you'd like to celebrate at dinner one evening. In addition, you may want to check out the
Gifts & Amenities Page under the Planning Center to order any special treats or celebratory decorations for your stateroom prior to your arrival on board.
As far as weather conditions in the Mexican Riviera in April, you can expect highs in the mid-80s (F) and lows in the mid-70s...with water temperatures a tad on the cool side. Yet, you'll probably want to head over to our friends at Weather.com to get the latest stats before you pack or sail.
Thanks for visiting me here on the Disney Moms Panel, and please let me know if I can help you out in any other way. Have a wonderful day and a magical vacation.
Bon voyage!
Andi