Tropical Cyclones are warm-core, low pressure systems that develop over the tropics or subtropical regions and have an organized circulation.

Depending on the ocean, a tropical cyclone could be named a hurricane (Atlantic/Eastern Pacific Oceans), a typhoon (Western Pacific Ocean) or a cyclone (Indian Ocean).

Favorable conditions for tropical cyclones to form include:

Warm ocean waters (at least 80°F) to about 150 feet below the surface.
An atmosphere that cools fast enough so it can be potentially unstable to moist convection.
Moist air at around 16,000 feet above sea level.
At least 300 miles from the equator. If the storm develops too close to the equator, there is not enough Coriolis Force to allow for the cyclone to spin.
Low amounts of vertical wind shear (the change in wind speed with height) between the levels of the atmosphere.

Tropical Cyclones form in seven tropical "basins" on a regular basis:

Atlantic Basin

Covers the North Atlantic Ocean, Gulf of Mexico and Caribbean Sea
Official Hurricane Season runs from June 1 through November 30. Peak activity is in early- to mid-September.

Northeast Pacific Basin

Covers Mexico towards the International Dateline
Tropical Cyclone Activity from late May through early November. Peak is late August and early September.

Northwest Pacific Basin

Covers the area from the International Dateline to Asia, including the South China Sea
Activity can occur year round, although less likely in February through early March. Peak is late August and early September.

North Indian Basin

Includes the Bay of Bengal and the Arabian Sea
Activity is from May through November, although strongest storms occur from April to June and late September through early December.

Southwest Indian Basin

Covers an area from Africa to 100 degrees east
Tropical Season begins in late October and reaches peak in mid-January and again in mid-February to early March. Activity usually ends in May.

Southeast Indian/Australian Basin

From 100 degrees east to 142 degrees east
Begins in late October and early November and peaks in mid-January and mid-February to early March. The season typically ends in May.

Australian/Southwest Pacific Basin

An area from 142 degrees east to about 120 degrees west
Season begins in late October and ends in early May. The peak is in late February or early March.