Hurricane season starts in June, but we usually don’t see major hurricanes — Category 3, 4 and 5 — until later in the year.
Hurricane Beryl, which was a Category 4 storm on Monday, is proving to be an exception — breaking many records this early into the season.
Over the weekend, Beryl became the strongest June hurricane on record, with maximum sustained winds of 140 mph. It was the first Category 4 storm to occur in June and the earliest Category 4 on record in the Atlantic Basin. On Sunday, Beryl rapidly intensified from a tropical storm to a major hurricane in just 42 hours. That’s both impressive and abnormal.
“To see a storm that far east and that strong this early is extremely unusual,” said University of Miami hurricane researcher Andrew Todd Hazelton.
Only six other storms have intensified as quickly as Beryl, and they all did so in September, when sea-surface temperatures in the Main Development Region of the Atlantic Basin are peaking for the year.
Meteorologist Will Redman, of the National Weather Service, said that several factors lead to rapid intensification.
“Of course water temperature plays a part. And there was a wave of Saharan dust, but it didn’t have an impact down where Beryl is,” Redman said.
Saharan dust, which sweeps off of North Africa at this time of year on very dry air, and travels across the Atlantic, can inhibit hurricane formation.
“There’s also a lack of wind shear right now,” Redman said.
Sea-surface temperatures in the tropical Atlantic are as warm as they usually are in September.
Hazelton, who conducts studies on how hurricane’s structure affects its strength, noted that the Atlantic Ocean’s exceptionally warm waters play a role, but there are other factors as well.
“The atmosphere is unusually favorable for this time of year. The warm sea-surface temperatures provide fuel,” said Hazelton, “but the other thing about the Atlantic compared to the rest of the tropics, it causes the global wind patterns to shift … so that there’s a lot less wind shear than normal for this time of year.”
Beryl was a small storm, in terms of diameter. This allows it to ramp up quickly, said Hazleton. It has since grown in size and its eyewall has reformed.
Beryl, which made landfall in the Grenadine Islands with winds speeds of 150 mph, is not the strongest storm to hit the eastern Caribbean. 2017’s Hurricane Maria, a September storm, bashed through the eastern Caribbean as a Category 5 with 165 mph wind, and holds the record for the strongest landfall in the Windward Islands.
To reach Category 5, Beryl would have to reach 155 mph. If it does, it will be only the second July Atlantic Basin storm to reach Category 5 status on record. The first was Emily in 2005.
According to NOAA, water temperatures along Beryl’s path are 85.5 degrees F, about 2 degrees warmer than the July average for that area. Warm surface water fuels hurricanes.
