Monsoon season in India runs from June to September. The monsoon is caused by differing temperature trends over the land and ocean. The southwest summer monsoon is attracted by a low pressure area that is caused by the extreme heat of  Thar Desert and adjoining areas during summer. During the monsoon season in India the wind direction reverses. Moisture-laden winds from the Indian Ocean come to fill up the void, because wind can’t pass through the Himalaya region, wind are forced to rise. The gain in altitude of the clouds results in a drop in temperature, bringing about rain.

When the southwest monsoon reaches India, it splits into two parts around the mountainous region of the Western Ghats in south-central India. One part moves northwards over the Arabian Sea and up the coastal side of the Western Ghats. The other flows over the Bay of Bengal, up through Assam and hits the Eastern Himalaya range.

The southwest monsoon reaches the coast of the southern state of Kerala around June 1. It usually arrives in Mumbai approximately 10 days later, reaches Delhi by the end of June, and covers the rest of India by mid-July. Every year the date of the monsoon’s arrival is the subject of much speculation. Despite numerous predictions by the meteorological department, it is rare that anyone gets it right though!

It is important to note that some regions receive more rain than others during the monsoon season. Out of India’s major cities, Mumbai receives the most rain, followed by Kolkata. Many cities become flooded at the start of the monsoon and during heavy downpours. This is due to drains being unable to cope with the volume of water, often because of trash that has built up over the summer and has not been properly cleared.

During the monsoon season in India, Delhi, Bangalore and Hyderabad receive comparatively less rain. Chennai doesn’t receive much rain at all during the southwest monsoon, as Tamil Nadu gets most of its rainfall from the northeast monsoon, from October to December. Kerala, Karnataka, and Andhra Pradesh also experience this monsoon, as well as heavy rainfall during the southwest monsoon.

The eastern part of Himalaya, Darjeeling and Shillong are one of the wettest areas of the whole world. This is because the monsoon picks up additional moisture from Bay of Bengal as it heads towards Himalayan range during monsoon season in India. Cherrapunji in Meghalaya is the place of getting the highest rainfall in the world.