The Atlantic hurricane season begins officially on June 1 and ends on November 30, every year. The east Pacific hurricane season officially lasts from May 15 until early November. Why are there these hurricane seasons?

During the winter and early spring, the ocean surface temperatures are not warm enough to generate the energy needed to develop and sustain a tropical cyclone. As spring turns into summer, the ocean's surface slowly heats up to the 80 degrees minimum temperature. (Note that the land may be hot during the spring while the ocean remains rather cool. The land heats and cools more rapidly than the ocean.) Once the ocean is warm enough, there are other atmospheric related elements that must be in place in order to produce tropical cyclones. All of these elements come together only a few weeks out the hurricane season- the traditional peak - about mid-August thru the end of September or so. Then, the ocean slowly cools and the upper atmosphere becomes less favorable for tropical cyclone development. Thus, we can see a hurricane in late October or even into November (Lenny anyone?). This does not mean there have never been tropical storms or hurricanes observed in the Atlantic outside of the 6 month hurricane season. In fact, they have occurred in all 12 months at one time or another.

Keep these rules of thumb in mind:

June- do not expect much activity.
July- a slight increase in activity.
August- especially mid to late August- a rapid increase in activity.
September- increased upswing in number of storms and hurricanes.
October- trend towards less activity- though still somewhat active in early October.
November- activity greatly diminishes.

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