An animation of images from NASA's Terra satellite shows the onset of India's monsoon season. The first, acquired on May 12, 2014, shows the Indian subcontinent almost cloud-free. In the second, captured on June 9th, storms systems are affecting the southern part of the country. (Source: NASA) As a vicious heatwave gripped much of India last week, causing temperatures to soar to 47 degrees C (116 F) or more in places, and prompting riots in protest of power outages, literally billions of people on the subcontinent awaited the arrival of the annual southwest monsoon. It was late. On average, the rains come to India's state of Kerala on June 1. This year, they arrived this past Friday, June 6th. The animation above, consisting of images from NASA's Terra satellite, offers a before and after look at the event. The first image was acquired on May 12th. It shows the entire Indian subcontinent almost free of clouds. Terra captured the second image yesterday, June 9th. Significant storminess is now seen affecting much of the southern part of the country. The southwest monsoon occurs as intense heating of the land during the warmest part of the year on the Indian subcontinent causes air to rise. This draws moist air from the southwest toward land. As that air rises and cools, clouds form and drop copious quantities of rainfall. The monsoon typically lasts until September. On Monday, India's Earth Sciences Minister Jitendra Singh said the monsoon was likely to bring below-average rainfall this year, raising fears that grain yields would be lower than normal and thereby raising food prices, according to Reuters. Of particular concern this year is the El Niño climatic phenomenon, which is likely to begin later in the summer. That could greatly reduce monsoon rainfall across central and northern India.