Since forming in the Bay of Bengal early Thursday, tropical Cyclone Mocha has intensified to a high-end Category 4 Atlantic hurricane, with sustained winds of 240kph (150mph).
Tropical cyclones (also known as hurricanes, typhoons and tropical storms depending on ocean basin and intensity), feed off ocean heat.
They need temperatures of at least around 27 degrees Celsius (80 Fahrenheit Fahrenheit) to form, and the warmer the ocean, the more moisture they can take up.
The waters in the Bay of Bengal are currently around 30 degrees Celsius (86 Fahrenheit Fahrenheit), about 2 degrees Celsius (3.6 degrees Fahrenheit) warmer than average for May.
Climate-change fueled sea-level rise adds to the risks, worsening storm surges from tropical cyclones and allowing them to travel further inland.