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Hurricane season is the period between 1 June and 30 November. At this time, conditions are most favourable for formation because a tropical cyclone and its growth into a hurricane requires:

  • A pre-existing weather disturbance with thunderstorms
  • Ocean temperatures at least 80F to a depth of about 150 feet
  • Winds that are relatively light throughout the depth of the atmosphere (low wind shear)
Birth of a hurricane

Heat and energy for the storm are gathered by the disturbance through contact with warm ocean waters. The winds near the ocean surface spiral into the disturbance's low-pressure area. The warm ocean waters add moisture and heat to the air, which rises. Bands of thunderstorms form, and the storm's cloud tops rise higher into the atmosphere. If the winds at these high levels remain relatively light (little or no wind shear), the storm can remain intact and continue to strengthen.

Tropical storms and hurricanes weaken when their sources of heat and moisture are cut off (as happens when they move over land) or when they encounter strong wind shear.

However, a weakening hurricane can re-intensify if it moves into a more favorable region, and the remnants of a hurricane that has already made land fall can still cause considerable damage.

Last Updated: 2010-08-15