Typically, tropical cyclones form at least 5.0 degrees of latitude north and south of the equator, or at least 300 nautical miles (556 km, 345 mi) from the equator. Within 5 degrees of the equator, tropical cyclogenesis is uncommon despite the presence of sufficiently warm sea surface temperatures and generally low wind shear, as a result of the lack of a strong Coriolis force, which causes cyclones to spin. On rare occasions, tropical cyclones can develop within 5ð of the equator, most commonly in the northwestern Pacific Ocean.
Various factors converge to produce a tropical cyclone, including sufficiently warm sea surface temperatures, low wind shear, ample moisture, and enough atmospheric instability to produce thunderstorms. In addition, for a tropical disturbance to develop into a tropical cyclone, it typically needs to be far enough away from the equator, where there is sufficient vorticity for the weather system to spin. This is because the vorticity generated by the Earth's rotation through the Coriolis force (called planetary vorticity) is zero at the equator and increases toward the poles. This lack of planetary vorticity can be overcome if there is sufficient relative vorticity produced via other means. One such phenomenon that can contribute to the development of low-latitude tropical cyclones is the equatorial westerly wind burst, which generates sufficient shear vorticity on both sides of the equator to support tropical cyclogenesis. Westerly wind bursts are most common in the equatorial Western Pacific Ocean.