Hampi has a largely warm and dry climate. Summer (March to May) sees very hot days, and winter (November to February) has pleasant days, cooling slightly over night. Monsoon season falls between June and August.
The best, and busiest, period to visit is between September and February (winter). Many tourist sites are outdoors, so it is best to avoid the rainy and scorching hot seasons. However if you can handle the weather these seasons are considered off peak, so they are quieter and less expensive.