Some El Niño Years Bring Early Hurricanes

While the official start of the Atlantic hurricane season is June 1, and all accounts point to a below-average season because of a super El Niño developing, some recent El Niño years have produced a pretty solid plot twist: pre-season storms.

We know that not all hurricane seasons have followed the traditional “hurricane season calendar” so to speak. And there actually have been some May storms pop up during stronger El Niño seasons.

(MORE: What Super El Niño Means For Hurricane Season)

May Storms During El Niño Seasons

There are some recent examples of a storm forming in May during an El Niño season:

Tropical Storm Arlene in 2023: While Tropical Storm Arlene technically wasn’t classified as a tropical system until June 1, it was active in the Gulf during the last few days of May. It was a short-lived system, only surviving until June 3. The system actually traveled south, before fizzling out, not making a direct U.S. landfall.

Tropical Storm Ana in 2015: This storm was the earliest recorded tropical system to make landfall in the U.S. The storm formed on May 8th and made landfall along the South Carolina coast on May 10, near Myrtle Beach. The storm brought winds of about 45 mph and more than 6 inches of rain. Several homes were flooded and even a few water rescues took place during Ana’s interaction with South Carolina.

What Causes Pre-Season Storms

While it might sound counterintuitive to have a pre-season storm during an El Niño season, it’s not impossible. The key wind shear that El Niño brings, hasn't quite kicked in yet, so we do have a small window where hurricane season could throw us a curveball.

There are two main ways a storm can form early:

Low Pressure: Oftentimes in the spring, we get areas of low pressure pushing across the southeastern U.S. This brings rounds of severe weather, that is very typical in the spring, however, sometimes, the low can drift down into the Gulf, where it taps into the warm water.

From there, it can gain tropical characteristics and become a tropical system. These will typically form right off the coast and be rather weak in nature. There’s usually not much time between formation and landfall.

Stalled Frontal Boundary: Another way early season storms can form is along a stalled frontal boundary. In the spring, fronts don’t always make it off the Southeast coast, and become stalled.

These stalled frontal boundaries create unsettled weather across the warm water of the Gulf and western Atlantic. This gives potential tropical systems a window of time to get organized and develop.

Again, most of these are weaker in nature and spin up right off the coast.

But just because they are weak, doesn’t mean they can’t cause problems. These quick developing tropical systems can bring serious flash flooding, especially if it is a slow-mover.

These early-season systems don’t always play by the same rules as the peak months of August and September, so it's a good idea to stay aware.

Does An Early Storm Mean A Busy Season?

It’s important to remember that early season storms do not mean a busy hurricane season.

There’s little correlation between when the first named storm forms and how busy the full season becomes. Some years with early May storms have gone on to be relatively quiet, while others that started late ended up extremely active.

The broader atmospheric pattern, including wind shear, ocean temperatures, and thunderstorm activity in the tropics, ultimately determines how the season unfolds. And we know during super El Niño seasons, that activity is typically down.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.