Interesting that the storm histogram I posted was just tweeted

![tweet](http://imageshack.com/a/img923/563/EN31bf.png)

The sharp peak is explained [here](http://www.noaa.gov/stories/peak-of-hurricane-season-why-now)

> "This minimum in the shear combines with favorable thermodynamics – ocean temperatures in the deep tropics that increase with each day of summer sun, warmer air temperatures, and increasing atmospheric moisture. When the dynamics and thermodynamics are in sync, as they often are from mid-August through early October, disturbances like African tropical waves can easily strengthen. "

So from what I can understand, the circulation along the equator diminishes in the late summer, allowing a strong buildup toward favorable thermodynamics, eventually reaching a tipping point?