I can't handle it when it is that hot at
Disneyland. The lines become unbearable to wait in, the parades too hot to enjoy, and you have to be very careful about heat exhaustion and heat stroke. If it it almost 100 in Disneyland (or higher) it always feels about 10 degrees hotter because of all of the concrete and crowds.
Luckily, these are usually "heat waves" for Anaheim, and soon enough it will return to a more acceptable level. If you are going in the summer, I can assure you that the weather will undoubtably be warm and sunny. It will be much better for your trip if the temps are in the 80's at the most, because the human body can only take so much heat.
I actually woke up this morning and thought "I feel sorry for people who planned their trip for today in Disneyland"--that is because a heat wave can really negatively impact a trip. I have been to Disneyland when it has been chilly and raining, and I have been there when it was 107+, and I would pick the rain and cooler temps any day! The heat made it impossible for us to even enjoy walking around the parks.