Actually, I've found that where you're coming from makes more difference than the actual temperatures!
We were there for Christmas last year and the first evening we arrived we went to downtown Disney. It was about 60 degrees and a beautiful evening, but you could tell the locals and southerners from us Canadians and northerners! About half the people were wandering around in shorts and t shirts, feeling quite comfy, and the others were bundled up in coats and hats and looking rather chilly. We parked our stroller with our summer clad toddler right next to another kid wrapped up in a winter coat and a blanket!
So maybe look at a chart comparing Anaheim's temps with your local report and go from there!