So I was studying Delhi and hence I have idea of all the seasons there.
1. Winter definitely is the best time to visit ( Nov to Feb ) however pollution is also at peak. You can enjoy all devious food, can visit all monuments, museums and may be Agra during your stay. 2. Summer especially from March to June it becomes really hot. However that can’t be the sole reason not to visit Delhi. But you have to ignore afternoons to visit places. 3. Rains are fine in Delhi.