TAMPA, Fla. (WFLA) — While much of the east coast was spared from any major tropical storm threats during the month of July, things could begin to change.
The Atlantic hurricane season is known for its slow starts, but things begin to pick up when we flip our calendars to August.
“Climatologically speaking, the busiest time of the season is August and September, where 60% of all storms form,” Max Defender 8 Meteorologist Amanda Holly said.
Since 1995, only five hurricane seasons have escaped the month without an Atlantic hurricane. The 2022 hurricane season was one of them.
The ‘campfire’ chart above shows the number of hurricanes (yellow area), and combined named storms and hurricanes (red area) that occur on each calendar day over a 100-year period. The chart shows the peak of the Atlantic hurricane season on Sept. 10, with most activity occurring between mid-August and mid-October.
So why are hurricanes more likely to form in August, September, and October?
African easterly waves
African easterly waves, often called tropical waves, are the building blocks for much of the tropical activity in the Atlantic. These vast waves of energy develop when warm, dry air in northern Africa mixes with the cooler, humid air over the Atlantic.
While dozens of waves roll off the coast of Africa every year, roughly one in five go on to produce an Atlantic basin tropical cyclone, according to the NHC.
Surges of dry air and dust carried across the Atlantic from the Saharan Desert normally squelch tropical development in the central and eastern Atlantic Basin. But those conditions tend to give way by August as the parade of African easterly waves gradually adds moisture, effectively creating favorable conditions for tropical storm development.
Wind shear inhibits tropical cyclones by removing the moisture they need from the area near their center. Shear also distorts the shape of a hurricane by essentially blowing its top away, so the vortex is tilted.
Storms with a tilted vortex are usually less efficient heat engines.
When the lack of these conditions is coupled with unusually warm surface water temperatures, hurricanes have free real estate to develop.
“August and September, this is really when things start to ramp up,” KXAN Chief Meteorologist David Yeomans said. “It seems like every single hurricane season about this time we’re saying, ‘There’s still more coming.’ I know hurricane season started a few months ago but this is when the bulk of the storms come.”
“Current forecasts are still calling for an ‘above-average’ season and if that is to verify, storm activity will likely ramp up over the next eight weeks,” Holly added. “As of Aug. 1, however, the only areas being watched over the next five to seven days are not a threat to the United States.”