I recently visited here with my family in the month of may. This hill station is situated in Dehradun, Uttarakhand. In the hot summer a perfect place to relax and feel the sense of heaven. I along with my family make a tour there, there is lot of places to visit. We visited George Everest , cloud end , kempty fall and mussorie lake. In all these places one thing is common , the environment is cold and surrounded by clouds. Even I feel that I am in sky.
So, I personaly recommended you to visit Mussorie in these hot days.