Regardless of your thoughts on climate change, the idea of multiple catastrophic hurricanes occurring at the same time is unsettling to say the least. Earlier this month, Hurricane Irma, Hurricane Jose and Hurricane Katia were simultaneously hovering over the Atlantic Ocean.

It’s only natural to interpret this collaborative onslaught of rain and wind as a sign that something is very, very wrong with Earth’s weather or atmosphere. But according to Live Science, the event of three hurricanes occurring at the same time is predicted to happen approximately once every ten years. It is simply the result of several natural but extreme weather patterns aligning, experts say.

How Does This Happen?

Scientists had even previously predicted September 10th to be the day when multiple hurricanes are most likely to occur. This year’s trio of storms seems more alarming than those of years’ past because at least two of them are hitting major American cities.

Speaking of the hurricane trio, lead seasonal forecaster with the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center Gerry Bell said “It’s not a random chance at all. Hurricanes aren't really a random phenomenon. They need conditions that are very conducive in order to form.”

We are also currently experiencing the warm phase of the Atlantic multi-decadal oscillation (AMO), an overarching weather pattern that rotates between the warm and cool phase every 25 to 40 years. The most recent cool phase took place from 1971 and 1995, when there were just two active hurricane seasons.

A hurricane season becomes active when two high-level weather patterns synchronize as they are naturally inclined to do in the aforementioned frequency. This is exactly what happened this year, when climate conditions are creating an excessively high amount of fuel for hurricanes.

Phil Klotzbach, an atmospheric scientist at Colorado State University, told Live Science that much of this fuel comes from the current temperatures of the Florida Straits, which reached 90 degrees Fahrenheit this year. Other high-level weather patterns include the especially light winds off the Atlantic and the especially high amount of moisture in the atmosphere.

Believe It Or Not, Other Decades Were Just As Bad

It’s unclear why these weather patterns align every ten years or so but the North Atlantic gyre, which churns out ocean currents between Iceland and the equator, may play a significant role.

The synchronization of the patterns, however, has been observed since the late 1800s. This might help explain why roughly the same amount of major storms have struck the US throughout previous decades. From 1851 to 1900, the US experienced an average of 6.2 major storms. There were six in the 1920s, five between 1991 and 2000, and seven from 2001 to 2010.

As for the total amount of hurricanes per year, numbers have remained relatively consistent as well. There have been 98 hurricanes from 2011 to 2017, about the same amount that occurred in the 1950s.

Does Climate Change Play A Role?

Many suspect climate change is primarily responsible for what seems to be an increase in storms, since ocean temperature is one of the climate conditions necessary for the formation of hurricanes.

But while rising sea levels might make the storms more destructive, scientists cannot safely say that it is responsible for this year’s particularly active hurricane season.

"It's a more nuanced process," Klotzbach said.

Blaming climate change could be more difficult in the future, he added, when the Atlantic Ocean is predicted to become colder than usual.