Rest of 2024 hurricane season will be more active than normal, weather officials warn (2024)

An above-average number of tropical storms, hurricanes and major hurricanes is still expected through the remainder of the 2024 hurricane season, the National Oceanic and Atmospheric Administration warned Thursday.

Near-record sea-surface temperatures in areas of the Atlantic Ocean where hurricanes form and a continued expectation that storm-enhancing La Nina conditions will kick in by September in the tropical Pacific are shaping those predictions.

The warm sea-surface temperatures provide the energy that fuels the thunderstorms that can come together and create tropical depressions, tropical storms and hurricanes.

The temperatures in the eastern Pacific Ocean, now roughly average, are expected to begin cooling by September, a condition called La Nina that reduces storm-disruptive upper level wind shear in areas of the Atlantic where hurricanes form.

While the early part of the season has been relatively quiet, NOAA now predicts the number of named storms, with winds of 39 mph or greater, to range between 17 and 24 in total. That's just one fewer than it forecast in May.

Of those, eight to 13 could become hurricanes, with winds of 74 mph or greater, including four to seven major hurricanes with winds of 111 mph or greater, which would be rated Category 3 through 5 on the Saffir-Simpson hurricane wind scale.

"The hurricane season got off to an early and violent start with Hurricane Beryl, the earliest Category 5 Atlantic hurricane on record,” said NOAA Administrator Rick Spinrad in a news release announcing the update. The update, he said, is "an important reminder that the peak of hurricane season is right around the corner, when historically the most significant impacts from hurricanes and tropical storms tend to occur.”

NOAA also says tropical Atlantic trade winds that could otherwise disrupt storm formation are weaker than normal.

The researchers also cite a more active west African monsoon season that is expected to deliver low-pressure tropical waves into the Atlantic. That will trigger thunderstorms that could develop into tropical systems as they head towards the Caribbean and the U.S. coastline.

The NOAA results mirror those published Monday by researchers at Colorado State University, who predicted 23 named storms for the season, with 12 reaching hurricane strength and six reaching major hurricane strength.

The hurricane season ends on Nov. 30.

Colorado State estimated there’s a 38% chance of a major hurricane – Category 3 or greater – making landfall somewhere on the Gulf Coast between the Florida panhandle and Brownsville, Texas, through the remainder of hurricane season, which ends on Nov. 30. That risk is significantly higher than usual. Between 1880 and 2020, the average chance that a major storm would make landfall was 27%.

The more active part of the hurricane season has historically been between mid-August and early October, with Sept. 10 the date on which the greatest number of tropical systems have been present in the Atlantic basin, based on records of storms between 1944 and 2020, according to the National Hurricane Center.

Whether that more-active part of the season is beginning earlier or ending later, and whether that’s related to cyclical increase in water temperatures in the Atlantic or the effects of global warming, is still up for debate.

Water temperatures throughout the Atlantic basin have been setting warmth records during the past two years, said Rick Knabb, hurricane expert with the Weather Channel and former director of the National Hurricane Center, during a Wednesday interview.

“At the end of July, we reached the climatological peak of Atlantic warmth— total ocean heat content— that usually peaks in early October,” Knabb said. “We already reached that value before August, and with the departure of El Nino, the conditions are very conducive for an extremely busy peak of the hurricane season.”

The switch to hurricane-enhancing La Nina conditions is a bit more predictable. That's a long-term weather cycle, though it does have blips— like the three-year run of cooler La Nina Pacific waters between 2020 and early 2023.

Usually, warmer El Nino conditions create more wind shear in the Atlantic that reduces storm formation. That didn’t happen last year, because of the record warm Atlantic water temperatures, Knabb said.

A troubling trend more likely linked to climate changeis new evidence that the forward speed of tropical cyclones is slowing down, near the U.S. coastline and when storms move onshore.

“Debby is another example of a very slow-moving tropical storm that is producing very impactful flooding that is much greater because of the storm meandering around the same areas for days on end,” Knabb said. Other similar storms in recent years have included Hurricane Harvey, which stalled over the Houston area in 2017, and Hurricane Sally, which impacted the Florida Panhandle and Alabama in 2020, he said.

Also concerned about the effect of warm water in the Atlantic, Caribbean Sea and Gulf on hurricane formation and intensification is Louisiana state climatologist Jay Grymes.

He calls the hot Gulf waters “high octane gasoline” for hurricanes.

“We’re seeing more atmospheric moisture and minimal wind shear, and any tropical wave moving into the Gulf’s atmospheric environment has the potential of spinning up,” he said.

Warmer temperatures allows the atmosphere to hold more water, which intensifies storms and produces more rainfall when the storms go onshore.

Adding to the danger in the Gulf is the potential for a storm to pass over the warmer, deep Loop Current or one of its offshoots, which could trigger rapid intensification, he said.

“We can sometimes get less than 48 hours heads up of a major hurricane threatening landfall,” he said. “They can take advantage of the Loop Current and blow up like Hurricanes Katrina and Rita.”

Grymes said he’s especially concerned this year that “tropical fatigue” will set in among Gulf Coast residents, as they’re bombarded with reports of the latest in tropical weather.

“From mid- to late August till the first week of October, we’re all going to be taking notice and sitting on the edge of our chairs,” he said. “Somehow, we have to keep a lid on our emotions until we really have something to worry about.”