Upstairs very warm during summer

Answer 1

 Science provides the best answer to this question. I will explain this to you with an example of air balloon which is always ready to go up into the sky. 

The hot molecules are lighter in weight then the cold one's. So warm molecules are always at the upper level then the cold molecules. 

Same goes with the house the upper portion is hotter then the lower portion of the house. 

So you should shift downstairs during summer instead of upstairs.