The Southwestern summer monsoons are prevalent from July through September
This occurs when the Thar Desert and the adjoining areas heat up during summers, creating a low pressure area over the northern and central Indian subcontinent. The moisture laden winds, drawn towards the Indian subcontinent are blocked by the Himalayas from passing to Central Asia. The Himalayas force these winds to rise. This results in precipitation as the rising moisture laden winds experience a drop in temperature
The Southwestern summer monsoons have two arms:
The Arabian Sea Branch of the Southwest Monsoon : that first hits the state of Kerala, thus making it the first state the country to experience monsoons
The Bay of Bengal Branch of Southwest Monsoon is directed towards northeastern India and pick up moisture from the Bay of Bengal region.