Atlantic Hurricane Season Peak: Sept. 10

By: Jon Erdman

Published: September 10,2013

 

 

 

 

 

The Season's Peak

What weather comes to mind first when we say "September"?  If you live near the East Coast or Gulf Coast, it probably should be "hurricanes."

This graph shows the progression of hurricane activity in the Atlantic basin from June through November. The climatological peak occurs on Sept. 10.

When looking at long-term averages of hurricanes and tropical storms in the Atlantic Basin, there is a broad maximum from late August through September. That said, there's a pronounced peak occurring around Sept. 10.
(MORE: Where Hurricane Season Peaks Twice)
So what is it about late August and September that optimizes the production of Atlantic tropical cyclones?

Optimizing the Season

First, the African easterly jet reaches its peak efficiency generating African easterly waves, a common "seedling" for Atlantic tropical cyclones in late August into early September.

A combination of factors lead to the climatological hurricane season peak.

Secondly is the atmosphere's thermodynamics, or the ability to generate thunderstorms. Sea-surface temperatures in the tropics tend to reach their peak in September, as waters have spent the summer absorbing the sun's warmth.
In addition, there's a relative minimum in deep-layer wind shear, which would otherwise tend to disrupt a central core of thunderstorms from clustering around an area of low pressure.

Origins of named storms from Sept. 1-10. Note virtually the entire Atlantic Basin is in play.

All these factors work in tandem most often from late August through September. Much of the Atlantic Basin, from just off the coast of west Africa to the Gulf of Mexico is "open for business" during this time.
Taken together, 61 percent of all Atlantic named storms since 1950 have been either in August or September.
So, how much of the season is left after "the peak"?