August and September; normally these are months when the Atlantic Ocean can be quite stormy. Hurricane Katrina left a trail of destruction through New Orleans in 2005. And in 1992, Hurricane Andrew did the same in Florida during this period. A few years ago, our own kingdom was affected when Hurricane Irma caused much damage and fatalities in the Windward Islands. Sint Maarten was especially hard hit.
Usually, the hurricane season is at its most intense around this time, but this year it is quiet. Dead quiet. On average, about seven hurricanes and fourteen storms rage annually over the Atlantic Ocean. This year, the count so far is six storms and not a single hurricane. It is the first time in over a century that no hurricane has been seen this late in the year. Interestingly, all of this has to do with the weather phenomenon El Niño.
"It is really very quiet. As hurricane scientists, I am a bit bored," jokes Nadia Bloemendaal, a scientist at the KNMI. "But it is not a given that nothing will form at all," she says. "The season runs until November 30. We remain on alert."
Record Number of Severe Hurricanes
The driving force behind the low number of storms and the absence of hurricanes is a very strong El Niño. This natural phenomenon suppresses the formation of hurricanes in the Atlantic Ocean. In the Pacific Ocean, the opposite happens.
On September 3, Copernicus satellites saw three hurricanes simultaneously in the Pacific Ocean for the first time since 2015:
The situation there this year is very different. Off the coast of Mexico, tropical storm Polo grew unusually quickly into a hurricane of the strongest category. It then weakened somewhat.
Polo is already the third very severe hurricane this year, matching the record for the Pacific Ocean. And the season there still lasts a while. Due to El Niño, not only do more hurricanes and storms form, but they also take different routes, so they more often end up in South Korea and Japan. The latter country was hit this week by Hurricane Dujuan.
Very Strong El Niño
During an El Niño, trade winds weaken over the Pacific Ocean. This causes relatively warm water to accumulate off the coast of South America. This is a natural variation that occurs every three to seven years.
The current El Niño is particularly strong. The water is already approximately at record temperature, while El Niño usually peaks in December. Although El Niño occurs in the Pacific Ocean, it has effects across the entire planet.
And not only in the sea but also in the atmosphere, many things happen due to El Niño, says hurricane expert Bloemendaal. For example, in the eastern Pacific Ocean, an area forms where air easily rises.
To form a storm, air must also rise. "In an area where the airflow naturally wants to go upward, such a storm gets a huge boost," says Bloemendaal.
NOS op 3 made this explanatory video about El Niño in 2024:
Over the Atlantic Ocean, the opposite happens during an El Niño. There is a descending airflow that actually works against the formation of storms. There are also large differences in wind speed and direction between the surface and high in the atmosphere, called wind shear. Storms form more easily when those differences are small.
Now that is much more difficult, Bloemendaal explains: "The wind shear now causes everything that tries to form to be blown apart immediately."
Warm Sea Water
El Niño is not the only change that influences the number of hurricanes. For example, in 2023 there was an El Niño and yet it was an active year for hurricanes over the Atlantic Ocean. "That was against our expectations as hurricane scientists," says Bloemendaal. "But the Atlantic Ocean's sea water was very warm then. That provided so much energy that forming hurricanes could break through the descending airflow."
This year, too, the Atlantic Ocean's sea water is relatively warm, but not as warm as in 2023.
If no hurricanes appear at all this year in the Atlantic Ocean, it would be the first time since the 1960s. That was when scientists began monitoring the Earth with satellites.
If you go further back in time, there have been years when people did not observe hurricanes in the Atlantic Ocean. But then the measuring instruments were more limited. For example, there were no satellites. So it cannot be ruled out that people missed hurricanes on the open sea that did not come near land.