Why are many good universities in the North or Northeast?

When you are warm you wear less and enjoy more . . . that is not conducive to the rigors of study. That said, Stanford is basically between 55 and 85 degrees all year long and they have killer studies (and a crazy ton of lazy students). On average, warm weather is not conducive to study. In rare environments you can get amazing things out of ppl in wonderful places to live.