We've done 2 spring break trips in March.....the day we pulled into Anaheim it was in the mid 90's (it was a record breaking day....oh yay for us....lol)
Most of the time, we secured a locker in the morning & we wore sweatshirts for the first couple hours, then stored the sweatshirts for the day & pulled them back out around dinnertime. We found using sweatpants & sweatshirts the best way to handle the kids. They wore shorts & tees underneath. Worked out perfectly to handle the temp changes.
We've also lucked out & never seen a drop of rain!!