Why Hurricane Beryl foretells a scary storm season

Hurricane Beryl’s explosive growth into an unprecedented early whopper of a storm shows the literal hot water the Atlantic and Caribbean are in – and the kind of season ahead, experts said.

Beryl smashed multiple records even before its major-hurricane-level winds approached land. The powerful storm is acting more like monsters that form in the peak of hurricane season thanks mostly to water temperatures as hot or hotter than the region normally gets in September, five hurricane experts told the Associated Press.

Beryl set the record for earliest category 4 with winds of at least 130mph (209km/h ) – the first-ever category 4 in June. It also was the earliest storm to rapidly intensify with wind speeds jumping 63mph (102km/h) in 24 hours, going from an unnamed depression to a category 4 in 48 hours.

Related: Four dead as category 5 Hurricane Beryl wreaks havoc across Caribbean

Late Monday, it strengthened to a category 5 , becoming the earliest hurricane of that strength observed in the Atlantic basin on record, and only the second category 5 hurricane in July after Hurricane Emily in 2005, the National Hurricane Center said. Category 5 storms have winds exceeding 157mph .

Beryl is on an unusually southern path, especially for a major hurricane, said University at Albany atmospheric scientist Kristen Corbosiero.

It made landfall Monday on the island of Carriacou with winds of up to 150mph, and is expected to plow through the islands of the south-east Caribbean. Beryl may stay near its current strength for another day before it begins weakening significantly, according to the late Monday forecast.

“Beryl is unprecedentedly strange,” said Weather Underground co-founder Jeff Masters, a former government hurricane meteorologist who flew into storms. “It is so far outside the climatology that you look at it and you say: ‘How did this happen in June?’”

Forecasters predicted months ago it was going to be a nasty year and now they are comparing it to record-busy 1933 and deadly 2005 – the year of Katrina, Rita, Wilma and Dennis.

“This is the type of storm that we expect this year, these outlier things that happen when and where they shouldn’t,” University of Miami tropical weather researcher Brian McNoldy said. “Not only for things to form and intensify and reach higher intensities, but increase the likelihood of rapid intensification. All of that is just coming together right now, and this won’t be the last time.”

Related: Hurricane Beryl: Caribbean leader calls out rich countries for climate failures as ‘horrendous’ storm makes landfall

Colorado State University hurricane researcher Phil Klotzbach called Beryl “a harbinger potentially of … even more potential threats and more – and not just a one-off – maybe several of these kinds of storms coming down later.”

The water temperature around Beryl is about 2F to 3.6F (1C to 2C ) above normal at 84F (29C), which “is great if you are a hurricane”, Klotzbach said.

Warm water acts as fuel for the thunderstorms and clouds that form hurricanes. The warmer the water and thus the air at the bottom of the storm, the better the chance it will rise higher in the atmosphere and create deeper thunderstorms, said the University at Albany’s Corbosiero.

Sea surface temperatures in the Atlantic and Caribbean “are above what the average September [peak season] temperature should be looking at the last 30-year average”, Masters said.

It’s not just hot water at the surface that matters. The ocean heat content – which measures deeper water that storms need to keep powering up – is way beyond record levels for this time of year and at what the September peak should be, McNoldy said.

“So when you get all that heat energy you can expect some fireworks,” Masters said.

This year, there’s also a significant difference between water temperature and upper air temperature throughout the tropics.

The greater that difference is, the more likely it becomes that storms will form and get bigger, said MIT hurricane expert Kerry Emanuel. “The Atlantic relative to the rest of the tropics is as warm as I’ve seen,” he said.

Atlantic waters have been unusually hot since March 2023 and record warm since April 2023 . Klotzbach said a high-pressure system that normally sets up cooling trade winds collapsed then and hasn’t returned.

Corbosiero said scientists are debating what exactly climate change does to hurricanes, but have come to an agreement that it makes them more prone to rapidly intensifying and increases the strongest storms.

“This is sort of our worst scenario,” Corbosiero said. “We’re starting early, some very severe storms … Unfortunately, it seems like it’s playing out the way we anticipated.”