Here are given some fast facts about the weather & climate of Kolkata:
Winter temperature: 12-27° C
Summer temperature: 24-38° C
Annual rainfall: around 160 cm
Humidity level is relatively high in summers
Best season to visit Kolkata is between October and march

The main seasonal influence upon the climate is the monsoon. Maximum rainfall occurs during the monsoon in August (306 mm) and the average annual total is 1,582 mm.

Early morning mists are common. Evening smog often occurs due to nighttime temperature inversions and mixing heights are generally restricted to below 500 m during the night.

Summer is dominated by strong south-westerly monsoon winds. Mean ventilation coefficients are greatest in the pre-monsoon (8,118 m2s-1) and monsoon (7,410 m2s-1) periods. Total duration of sunshine is 2,528 hours per annum with maximum insolation occurring in March