Most of the rides in the Magic Kingdom have outdoor (though usually covered) queues, at least some of the time. You may get a breeze there, but it's still quite hot on warm days. You may need to get a Guest Assistance pass for your son for the rides with outdoor queues, since heat is an issue. Off the top of my head, here's the Indoor/outdoor situation for both rides and queues (as you'll generally spend more time in the queue than on the actul ride).
MAGIC KINGDOM
Buzz Lightyear: Indoor ride, indoor/outdoor queue
Carousel of Progress: Indoor ride, no queue
Space Mountain: Indoor ride, indoor queue
Astro Orbiters: Outdoor ride, outdoor queue
TTA Peoplemover: Outdoor ride, outdoor queue
Tomorrowland Speedway: Outdoor ride, outdoor queue
Stitch: Indoor ride, indoor queue
Monster's Laugh Floor: Indoor show, indoor queue
Mad Tea Party: Outdoor ride, outdoor queue
Pooh: Indoor ride, outdoor queue
Dumbo: Outdoor ride, outdoor queue
Cinderella's Carousel: Outdoor ride, outdoor queue
Snow White: Indoor ride, outdoor queue
Philharmagic: Indoor show, indoor queue
Peter Pan: Indoor ride, outdoor queue
Small World: Indoor ride, outdoor queue
Haunted Mansion: Indoor ride, outdoor queue
Hall of Presidents: Indoor show, indoor queue
Country Bears: Indoor show, indoor queue
Splash Mountain: Indoor/outdoor ride, indoor/outdoor queue
Big Thunder: Outdoor ride, outdoor queue
Pirates: Indoor ride, Indoor queue
Aladdin's Carpets: Outdoor ride, outdoor queue
Jungle Cruise: Outdoor ride, outdoor queue
Tiki Room: Indoor show, Outdoor pre-show
ANIMAL KINGDOM
Kilimanjaro Safari: Outdoor ride, outdoor queue
Everest: Outdoor ride, outdoor queue
Flights of Wonder: Outdoor show, no queue to speak of
Nemo: Indoor show, outdoor queue
Festival of the Lion King: Indoor show, outdoor queue
Bug's Life: Indoor show, Indoor/outdoor queue
Dinosaur: Indoor ride, indoor queue
Primeval Whirl: Outdoor ride, outdoor queue
Kali River Rapids: Outdoor ride, outdoor queue
Hollywood Studios:
Beauty and the Beast: Outdoor show, outdoor queue
Fantasmic: Outdoor show, outdoor queue
Tower of Terror: Indoor ride, indoor queue
Rock and Rollercoaster: Indoor ride, outdoor/indoor queue
Toy Story Midway Mania: Indoor ride, indoor (and sometimes outdoor) queue
Star Tours (closed): Indoor ride, indoor queue
Muppets 3D: Indoor show, indoor queue
Lights, Motors, Action: Outdoor show, outdoor queue
Backlot Tour: Outdoor ride, outdoor queue/pre-show
Sounds Dangerous (mostly closed): Indoor show, outdoor queue
EPCOT
Spaceship Earth: Indoor ride, outdoor queue
Nemo: Indoor ride, indoor (sometimes extending outdoors) queue
Living with the Land: Indoor ride, indoor queue
Circle of Life: Indoor show, indoor queue
Soarin': Indoor ride, indoor queue
Imagination: Indoor ride, indoor queue
Innoventions: indoors
Ellen's Energy Adventure: Indoor ride, indoor queue (usually)
Mission Space: Indoor ride, indoor queue (can extend outdoors)
Test Track: Indoor/outdoor ride, indoor queue
The World Showcase attractions have already been covered by OPs. Most of the shows in World Showcase (Off-Kilter, acrobats, taiko, etc) are outdoors, as is the America Gardens Theatre.
Hope that helps!