2023 Hurricane Season Outlook Update: Record Atlantic Ocean Warmth Could Override El Niño Influence

T​he 2023 Atlantic hurricane season may be one of the most active for any El Niño season on record, due to record-warm Atlantic Ocean water temperatures, according to the latest outlook.

A​n update released Thursday by The Weather Company and Atmospheric G2 calls for 20 total storms, 10 of which are expected to become hurricanes and five of which will reach at least Category 3 status.

This is an increase of three storms, one hurricane and one major hurricane since their previous outlook, which was released in mid-June. The increase in storms and the overall outlook takes into account five storms that have already occurred this year.

This is similar to a forecast released earlier in July by the Colorado State University tropical forecast team, and is well above the latest 30-year average tallies.

Don formed in July, Arlene, Bret and Cindy formed in June and an unnamed subtropical storm developed in January that was retroactively upgraded by the National Hurricane Center in May.

The fifth storm of the season doesn't typically arrive until late August, according to the NHC.

Two major factors are in play this hurricane season: a strengthening El Niño and extremely warm Atlantic water temperatures.

Atlantic Ocean Warmth Is Still Off The Charts

O​ne of those factors is dominating right now.

A major contributor to the planet's hottest June on record was record warmth in the Atlantic Basin where hurricanes and tropical storms form. That has continued into July.

A​ccording to AG2 meteorologists Todd Crawford, Ed Vallee and James Caron, an index that tracks the warmth of the North Atlantic Ocean known as the Atlantic Multidecadal Oscillation (AMO) is at its highest level since at least 1950.

"This anomalous warmth is why CSU's seasonal hurricane forecast has increased, despite (a) likely robust El Niño," wrote Phil Klotzbach, tropical scientist and lead of the CSU forecast team, in a tweet ​prior to the CSU outlook release earlier in July.

The scope and magnitude of this anomalous warmth as of late July was well beyond what was seen in other warm ocean hyperactive hurricane seasons such as 2020, 2017 and 2005.

This is important because assuming other factors are equal, the deeper and warmer the ocean water, the stronger a storm or hurricane can become.

T​ypically, there is a cooler pocket of water early in hurricane season from the Cabo Verde Islands to Bermuda to the northern Leeward Islands. Tropical waves reaching this pocket of colder waters often succumb to otherwise hostile conditions.

T​his warmth we're seeing right now is more typical of the peak of hurricane season, with plenty of time for additional warming.

This unusually warm water was one factor behind the development of tropical storms Bret and Cindy, the first time two storms developed over the strip of the Atlantic Ocean between Africa and the Lesser Antilles in June.

But What About El Niño?

Another factor could have the opposite effect of the warm Atlantic waters.

Pacific equatorial waters had been cooler than average during the past three hurricane seasons – a condition known as La Niña. B​ut that long-lasting La Niña finally disappeared.

A​n El Niño that was declared in early June is now of moderate strength and could gain a bit more intensity by the peak of hurricane season, August through October, according to the latest outlook from NOAA issued in mid-July.

The reason this strip of water far from the Atlantic Basin matters is that it's one of the strongest influences on hurricane season activity.

In El Niño hurricane seasons, stronger shearing winds often occur over at least the Caribbean Sea and some adjacent parts of the Atlantic Basin. This tends to limit the number and intensity of storms and hurricanes, especially if the El Niño is stronger, as we investigated in a March article.

H​owever, since this El Niño is still in its early stages, it hasn't yet flexed its muscles on the weather pattern described above, but may do so increasingly during the remainder of the hurricane season.

"​(A) high chance of a robust El Niño is why CSU's hurricane forecast is not for even more activity given (a) record warm Atlantic," wrote Klotzbach in another Tweet.

The AG2 forecast team also noted a tendency in El Niño hurricane seasons for fewer Gulf of Mexico storms and more storms to either curl north, then northeast out into the open Atlantic Ocean or to impact parts of the East Coast.

T​hat's because the Bermuda high tends to be weaker, and it's also due to a more persistent dip in the upper-level winds in the southeastern U.S. during El Niños, according to the AG2 forecast team.

Which Competing Factor Will Win?

"​The combination of an incipient El Niño and historically warm North Atlantic SSTs (sea-surface temperatures) is unprecedented in the recent record," wrote the AG2 forecast team in their outlook.

That's not providing decent matches from past years to use as analogs, making this year's outlook particularly challenging.

One plausible scenario to the rest of the hurricane season is more storm tracks in the eastern and central Atlantic Ocean, feeding off the unusually warm water, but perhaps fewer in the Caribbean Sea and Gulf of Mexico, assuming more hostile wind shear from El Niño kicks into gear.

Record Active El Niño Hurricane Season?

The 20 storms, 10 hurricanes, five major hurricanes forecast from AG2 sounds really active.

While the ultimate impact of any hurricane season depends on how many storms and hurricanes strike land, we wanted to provide some additional perspective on how aggressive this forecast is.

O​nly four hurricane seasons on record had at least 20 storms: 2020 (30), 2005 (28), 2021 (21) and 1933 (20). That's notable, but there has been an upward trend in the number of storms in recent decades, mainly due to better detection of those storms, that has made 20 storms in a single season within reach more often.

S​ixteen other seasons have had at least 10 hurricanes, most recently in 2020 (13 hurricanes) and 2017 (10 hurricanes). So that's busy, but not all that unusual.

W​e then examined the 21 previous El Niño hurricane seasons since 1950.

T​hose 21 seasons averaged 10 storms, five hurricanes and two that reached at least Category 3 intensity. We would consider that a relatively quiet season today.

T​he most of any El Niño hurricane season was 18 storms and 12 hurricanes. Both happened in 1969, the year Category 5 Hurricane Camille made a catastrophic strike on the Gulf Coast.

The most Category 3 hurricanes of any El Niño season was six in 2004, including Florida's infamous foursome (Charley, Frances, Ivan and Jeanne).

B​ut both 1969 and 2004 were weak El Niños.

What if we examine only the moderate to strong El Niño seasons, given the current El Niño's strength? Those 11 such moderate to strong El Niño hurricane seasons averaged nine storms, four hurricanes and one to two that reached at least Category 3 intensity.

T​he most in any such season was 12 storms (2002 and 1951), eight hurricanes (1951) and three Category 3-plus hurricanes (1963 and 1951).

S​o 2023 could be among the most active hurricane seasons to occur during an El Niño in modern records, particularly when considering moderate or strong El Niños.

"​We suspect this won't be your father's El Niño hurricane season," wrote the AG2 forecast team in their outlook.

P​repare The Same Every Hurricane Season

What these outlooks cannot tell you is whether or not your area will get struck this season and when that might happen.

A season with fewer storms or hurricanes can still deliver the one storm that makes a season destructive or devastating.

In 2015, one of the strongest El Niños on record reduced the hurricane tally to four that season. However, one of those was Joaquin, which devastated the central Bahamas.

And i​t doesn't take a hurricane to be impactful, especially regarding rainfall flooding.

Also in the 2015 season, T​ropical Storm Erika was ripped apart by wind shear and dry air near the Dominican Republic. But before that happened, it triggered deadly and destructive flooding in Dominica.

These outlooks serve as a reminder that the time to be ready for hurricanes is now. Information about hurricane preparedness can be found here.

M​ORE ON WEATHER.COM:

C​hanges You'll See In Hurricane Forecasts This Season

W​hen The Last 'Quiet' Hurricane Season Happened

F​acts About Each Of The 2023 Atlantic Hurricane Season Names

'​Ian', 'Fiona' Retired As Hurricane Names

2​022 Hurricane Season Recap: Florida's Luck Ran Out

Jonathan Erdman is a senior meteorologist at weather.com and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7. Follow him on Twitter and Facebook.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.