The rainy season in India starts with the onset of the southwest monsoon in June and continues till the middle of September!

This is also called the monsoon season, the southwest monsoon season, the wet season and the hot-wet season. The weather conditions all over the country change with the onset of the monsoon winds. High heat, high humidity, extensive clouding and several spells of moderate to heavy rain with strong surface winds are the chief characteristics of this season.

Reference:http://www.yourarticlelibrary.com/season/rainy-season-the-rainy-season-in-india-2548-words/13832