Dry Air and Wind Shear Limiting Tropical Development in the Atlantic

The Atlantic basin has been largely asleep over the last few weeks. While a few disturbances have threatened to organize into a named storm, nothing has come to fruition in September. What is the reason behind the quiet start to what is typically the most active month in the Atlantic basin?

All is Quiet in the Atlantic Basin

The climatological peak of the Atlantic hurricane season is September 10. But you would never know that by checking out the satellite over this part of the world's oceans. Hurricane experts are predicting that the September slump could persist well into next week before the action picks up again.

The calm conditions over the Atlantic are certainly a historical anomaly. Going back to data from the World War II era, the middle of September is generally the busiest time of the season for tropical weather in this ocean. This activity is easily explained by warmer ocean water temperatures and low amounts of disruptive wind shear.

Going back to 2024 during this same week, the National Hurricane Center (NHC) was busy tracking Hurricane France as it made its approach toward the Gulf Coast, a tropical depression that would later become Gordon, and three additional areas of development in the basin.

It was even busier five years ago when there was one point that hurricane watchers were tracking five features coming in at tropical depression strength or higher. This volume of activity had only happened once since 1971.

Understanding Why the Atlantic Has Been So Quiet

Why has the Atlantic basin hit the snooze button during this typically busy time? Climatologists are blaming frequent rounds of dry air that are pushing across the main development area between the African and the Lesser Antilles. The large swaths of dry air work to put a lid on thunderstorm development, further inhibiting the formation of tropical systems. This means that the tropical waves that eject off the coast of Africa are quickly snuffed out before they have the chance to move across the Atlantic and intensify.

This exact situation happened last weekend when forecasters had been warning that the latest tropical wave had a high chance of development. Instead, Invest 91L got caught up in a mass of dry air and petered out.

In addition to the prevalence of dry air, higher amounts of wind shear circulating in the southwestern, eastern, and central Atlantic have torn apart storms as they come to life. Wind shear is also serving as a roadblock for tropical weather development in the Gulf, despite the exceptionally warm temperatures.

As of Tuesday, it has been 11 days since the last tropical storm roamed the Atlantic. The Atlantic hurricane season has now fallen behind the typical pace by about two tropical storms and two hurricanes. The overall intensity of the activity, using the metric known as the ACE index, is also lagging about 25% slower than what is normal by this point in the season.

Hurricane Erin is the only storm to reach this status in 2025. While Erin made it all the way to a Category 5 designation, the storm avoided a direct landfall. The greatest impacts came in the form of flooding rainfall to the Leeward Islands and indirect effects such as rip currents and winds to the East Coast.