The climate in Mumbai throughout the year is temperate-from being hot and humid in summer to being pleasant in winter. Its' neither too hot nor too cold. It rains quite heavily during the monsoon months of June, July and August. The climate is cooler in IIT than its surroundings - the reason is that it is located between two lakes and also surrounded by greenery.
Winter in Mumbai:
During December and January the climate in Mumbai is pleasant. The air temperature will be around 25 degree C (75% relative humidity) in the daytime and around 15 degree C at night.
Summer in Mumbai:
During May and June the climate is becomes hot and humid in the afternoons. The air temperature will be around 35 degree C (90% relative humidity) in the daytime and around 25 degree C at night.
Monsoon in Mumbai:
The monsoon rains hit Mumbai in the month of June. The rains are quite heavy and last till the end of August. The climate becomes pleasant. The air temperature will be around 30 degree C (80% relative humidity) in the daytime and around 20 degree C at night.