Tropical Cyclone Formation Regions



There are seven tropical cyclone "basins" where tropical cyclones form on a regular basis:

Atlantic basin
North Atlantic Ocean, the Gulf of Mexico, and the Caribbean Sea		 The Hurricane season is "officially" from 1 June to 30 November. Peak activity is in early to mid September. Once in a few years there may be a tropical cyclone occurring in May or December.
See the probabilities for the Atlantic Basin by month.
Northeast Pacific basin
Mexico to about the dateline		 A broad peak with activity beginning in late May or early June and going until late October or early November with a peak in storminess in late August/early September.
Northwest Pacific basin
From the dateline to Asia including the South China Sea		 Occur all year round regularly though there is a distinct minimum in February and the first half of March. The main season goes from July to November with a peak in late August/early September.
North Indian basin
Including the Bay of Bengal and the Arabian Sea		 A double peak of activity in May and November though tropical cyclones are seen from April to December. The severe cyclonic storms (>74 mph / 119 km/h winds) occur almost exclusively from April to June and again in late September to early December.
Southwest Indian basin
From Africa to about 100°E		 Beginning in late October/early November, reaching a double peak in activity-one in mid-January and one in mid-February to early March, and then ending in May.
Southeast Indian/Australian basin
100°E to 142°E		 Beginning in late October/early November, reaching a double peak in activity-one in mid-January and one in mid-February to early March, and then ending in May. The Australian/Southeast Indian basin February lull in activity is a bit more pronounced than the Southwest Indian basin's lull.
Australian/Southwest Pacific basin
142°E to about 120°W		 Begins in late October/early November, reaches a single peak in late February/early March, and then fades out in early May.

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