The climate in India varies widely, depending on the time of year and where we are, from the arid Rajasthan desert to the Assam Mountains, allegedly the wettest area on the planet. But basically there are 3 seasons.
The cold (Dec-Feb), when some northern areas (Delhi, for example) reach very low temperatures and Darjeeling attracts large numbers of people to ski.
The hot (Mar-Mai), which especially from April, fires to normal temperatures around 40º in most cities.
The humid (Jun-Sep), also known as the monsoon season, begins in the south and sweeps the rest of the country with heavy rain and thunderstorms.