La Nina's role explained in Atlantic hurricane season

1 of 3 | Large parts of New Orleans were flooded weeks after several levees failed in the wake of Hurricane Katrina in September 2005. That hurricane occurred around the onset of La Niña conditions. File Photo by Bob McMillan/FEMA Photo for UPI | License Photo
Most people associate La Niña with warmer winters or drought in the southern United States, but its influence stretches far beyond the winter months. When La Niña sets in during hurricane season, it has the potential to dramatically increase both the number and strength of tropical storms and hurricanes in the Atlantic basin.
La Niña is part of the El Niño-Southern Oscillation (ENSO) cycle and is defined by lower-than-average sea-surface temperatures in the eastern Pacific Ocean near the equator. Although the phenomenon originates far from the Atlantic Ocean, it disrupts global weather patterns in a way that suppresses wind shear across much of the tropical Atlantic.
This matters because vertical wind shear -- the change in wind speed or direction with height - tends to prevent tropical systems from organizing. When shear is reduced, clusters of showers and thunderstorms are more likely to organize, strengthen and turn into tropical storms and hurricanes.
"La Niña increases the number of hurricanes that develop and allows stronger hurricanes to form," said AccuWeather Lead Hurricane Expert Alex DaSilva. "It also raises the chances for the continental U.S. and the Caribbean Islands to experience a hurricane."
During La Niña years, meteorologists often observe more named storms, more major hurricanes and higher accumulated cyclone energy (ACE), a measure of the strength and duration of storms over time. The odds of U.S. landfalls also increase, particularly for the Gulf Coast and Southeast.
Two of the most active hurricane seasons in modern history occurred around the onset of La Niña conditions: 2005 and 2020. In 2005, Hurricane Katrina devastated the Gulf Coast, and the official storm naming list was exhausted for the first time, prompting the use of Greek letters.
In 2020, the Atlantic basin experienced a record-breaking 11 storms that made direct landfall on U.S. soil, including Hurricane Laura.
As for 2025, La Niña is not expected during the early part of the hurricane season. However, forecasters are watching for signs that it could emerge later in the year.
"If we trend toward La Niña late in the hurricane season, we could see an active end to the season, similar to what we saw last year," DaSilva said.
Complicating matters is the presence of unusually warm water in the Atlantic Ocean, which increases the risk of rapid intensification -- a dangerous trend in which storms gain strength quickly just before landfall.
One of the biggest factors for tropical development in 2025 is the abundance of warm water available to fuel storms.
"The water temperatures across most of the Atlantic are above average for this time of the year," DaSilva said. "They're not quite as warm as what we saw last year and in 2023, but they're still well, well above average."
If La Niña arrives in the second half of the season and combines with this ocean heat, the Atlantic could be primed for a particularly volatile stretch during the peak hurricane months of September through November.
La Niña doesn't guarantee an above-average season, but it dramatically shifts the odds in that direction. And for coastal communities, that makes understanding its influence more important than ever.

Try Our AI Features

Explore what Daily8 AI can do for you:

Learn with AIFact CheckingText to SpeechAI Summary

Related Articles

Newsweek

9 hours ago

• Newsweek

Millions of Americans Warned of 'Dangerous, Life-Threatening' Conditions

Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources. Newsweek AI is in beta. Translations may contain inaccuracies—please refer to the original content. AccuWeather meteorologists are warning of "dangerous, life-threatening" conditions for millions of Americans as a heat wave is moving across large portions of the U.S. later this week, with temperatures expected to top 100 degrees Fahrenheit across several states. Millions of Americans are expected to face major or extreme heat risks in the coming days, with the National Weather Service projecting over 152 million affected on June 23. Why It Matters Extreme heat is the deadliest weather hazard in the United States, posing serious health risks nationwide. Over 200 people died of heat-related illnesses in the U.S. last year. Since 1979, more than 14,000 Americans have died from heat-related causes, according to the Environmental Protection Agency. A "heat dome" is moving through the U.S., later this week, with millions of Americans across a range of large cities to be impacted. Several extreme heat warnings and heat advisories have been issued across cities and states. The heat wave coincides with the longest days of the year, with Friday marking the summer solstice. What To Know "The highest temperatures so far this year will combine with increasing humidity and intense summer sunshine to create dangerous, life-threatening conditions for roughly 170 million people," AccuWeather meteorologists said about the upcoming heat wave. The NWS predicts that on June 21, 62.5 million will be under major or extreme heat risk, 141 million on June 22, 152 million on June 23, 144 million on June 24 and 105 million by June 25. The NWS Weather Prediction Center similarly warned that "extremely dangerous levels of heat" are likely over the Central and Eastern U.S. These levels "may exacerbate the heat health impacts, especially by midweek," a June 20 message from the center said. The sun rises behind the skyline of midtown Manhattan and the Empire State Building in New York City, a day ahead of the summer solstice and an expected heatwave on June 19, 2025, as seen... The sun rises behind the skyline of midtown Manhattan and the Empire State Building in New York City, a day ahead of the summer solstice and an expected heatwave on June 19, 2025, as seen from Jersey City, New Jersey. More Photo byAreas of particular concern include the Ohio Valley, eastern Great Lakes, interior South and much of the East Coast, according to a warning from the NWS. In addition to record-high temperatures, those regions are expected to "lack overnight cooling," which will "significantly increase the danger." Heat index values—how the temperature feels to the body when humidity is factored in—were expected to reach triple digits in some areas that have Extreme Heat Warning issued by the NWS. Large U.S. cities have begun issuing warnings to residents ahead of the heat wave. In Annapolis, Maryland, officials posted an alert on the city's website and announced the activation of cooling centers "to provide temporary relief from extreme heat conditions and help prevent heat-related illnesses," as temperatures are expected to exceed 100 degrees and may reach 110. What People Are Saying AccuWeather Chief Meteorologist Jonathan Porter said: "Extreme heat is tragically the leading cause of weather-related fatalities in America. There is an amplified risk of heat-related illnesses because this is the first heat wave of the year for millions of people, and their bodies are not yet acclimated to this type of heat and humidity." Ben Noll, a meteorologist for The Washington Post, said on X, Wednesday: "A heat dome will form over central states on Friday before expanding and intensifying. Heat domes are large and strong heat-trapping lids of high atmospheric pressure. This one will last around a week, with numerous temperature records expected to fall." AccuWeather Chief On-Air Meteorologist Bernie Rayno said: "It will be exceptionally warm at night with little relief once the sun goes down. Many urban areas may struggle to drop below 80 at night, and that can take a toll on the body without air conditioning." Kevin J. Simmons, Director of the City of Annapolis Office of Emergency Management said in a Friday statement: "Heat waves like this one pose a serious risk, especially for our most vulnerable neighbors. We are asking all residents to take this heat seriously. Check on your neighbors, stay hydrated, limit outdoor activity, and know where to go if you need to cool down. Our goal is to keep everyone safe and informed throughout this dangerous weather event." National Weather Service wrote in an X, formerly Twitter, post on Wednesday: "Triple-digit heat indices will be common through next week, with oppressive humidity. Record-breaking heat will be dangerous to those working and playing outdoors so take precautions." What Happens Next The NWS warns, "This level of heat can be hazardous to anyone without effective cooling and/or adequate hydration, especially those engaging in lengthy outdoor activities."

UPI

9 hours ago

• UPI

North Carolina woman predicts $200,000 lottery win

A North Carolina woman told her husband lottery luck was in their future just before they scored a $200,000 lottery prize. File Photo by John Angelillo/UPI | License Photo June 20 (UPI) -- A North Carolina woman predicted a lottery jackpot was in her future just before winning $200,000 from a scratch-off ticket. Hubert resident Sylvia Wells told North Carolina Education Lottery officials she voiced her prediction to her husband just before they bought a pair of scratch-off tickets from the Handy Mart on Western Boulevard in Jacksonville. "We bought his favorite ticket and my favorite ticket," she said. Her husband's selection, a Diamond 10X ticket, turned out to be a $200,000 winner. "I was like, 'I told you we were going to do it,'" Wells recalled saying. "We did it." Wells said the winnings will go toward buying some land.

Bloomberg

10 hours ago

• Bloomberg

Intense Heat to Push Biggest US Grid's Power Use to 12-Year High

Electricity use on the biggest US grid, which serves nearly a fifth of Americans from Washington DC to Illinois, is expected to climb to a 12-year high as intense heat spurs air conditioning needs. A heat wave will start baking the mid-Atlantic on Saturday with temperatures climbing to 100 F (38 C) in Washington on Monday, 13 degrees above average, according to Households and businesses relying on the grid managed by PJM Interconnection LLC may use as much as 158.5 gigawatts at about 5 p.m. ET, according to the system operator. That would make it the highest hourly peak demand since July 2013 and is above this summer's anticipated high, PJM data show.