In general, warm ENSO episodes are characterized by an increased number of tropical storms and hurricanes in the eastern Pacific and a decrease in the Gulf of Mexico and the Caribbean Sea (Atlantic). La Niņa (cold conditions in the equatorial Pacific) favor hurricane formation in the Atlantic with the opposite happening in the Eastern Pacific.
During El Niño episodes, the tropospheric vertical shear is increased in the Atlantic, inhibiting tropical cyclone genesis and intensification.
In the Western Pacific basins there is a change in location of tropical cyclones without a total change in frequency during a El Niño event. The opposite occurrs during La Niņa events. There is also the tendency for the tropical cyclones to form closer to the equator during El Niņo events than average.