I second the Robeez shoes, they are great! DD has several pairs, they hold up well and look so pretty.
They do have sandals which have holes to make them more "airy", however they might still make you LO's feet hot/sweaty, depending on how hot it is in your area. DD can't wear the regular Robeez shoes on super hot days cuz they make her feet hot and more sweaty.
Check their website occasionally, they sometimes have free shipping for order of 2 prs and up. I recently picked up 2 prs in the next size up for DD. Can't wait for her to fit into them, they're soooo cute.