The list ranked according to highest death toll. The deadliest Cyclones, Hurricanes & Typhoons occurred in Bangladesh in 1970 and nearly 500.000 people lost their lives. A tropical cyclone is a storm system characterized by a low pressure center and numerous thunderstorms that produce strong winds and flooding rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air. They are fueled by a different heat mechanism than other cyclonic windstorms such as nor'easters, European windstorms, and polar lows, leading to their classification as "warm core" storm systems.