During 2003, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 129 systems formed with 85 of these developing further and were named by the responsible warning centre. The strongest tropical cyclone of the year was Cyclone Inigo, which was estimated to have a minimum barometric pressure of 900 hPa (26.58 inHg) and was tied with Cyclone Gwenda for being the most intense recorded cyclone in the Australian region in terms of pressure, with the possible exception of Cyclone Mahina. So far, 26 Category 3 tropical cyclones formed, including six Category 5 tropical cyclones formed in 2003, tying 2021. The accumulated cyclone energy (ACE) index for the 2003, as calculated by Colorado State University was 833 units.

During 2021, tropical cyclones formed in seven major bodies of water, commonly known as tropical cyclone basins. Tropical cyclones will be assigned names by various weather agencies if they attain maximum sustained winds of 35 knots. During the year, one hundred forty-five systems have formed and ninety-one were named, including one subtropical depression and excluding one system, which was unofficial. One storm was given two names by the same RSMC. The most intense storm of the year was Typhoon Surigae, with maximum 10-minute sustained wind speeds of 220 km/h (140 mph) and a minimum pressure of 895 hPa (26.43 inHg). The deadliest tropical cyclone was Typhoon Rai, which caused 410 fatalities in the Philippines and 1 in Vietnam, while the costliest was Hurricane Ida, which caused an estimated $75.25 billion USD in damage after striking Louisiana and the Northeastern United States.