Understanding El Niño, La Niña, and Their Impact on U.S. Hurricanes

The terms "El Niño" and "La Niña" have become increasingly familiar to many people, especially those living in areas such as Texas prone to hurricanes.

These weather phenomena play a significant role in shaping global weather patterns and can greatly influence the severity and frequency of hurricanes in the United States.

Let’s explore what El Niño and La Niña are, how they affect hurricane season, and why predictions are being made for a rough 2024 season with more than double the average number of tropical cyclones due to La Niña and near-record ocean temperatures.

What is Hurricane Season?

Hurricane season in the United States typically runs from June 1st to November 30th, with peak activity occurring between August and October.

During this time, conditions in the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico become more favorable for the development of tropical cyclones, which can grow into hurricanes.

These storms are fueled by warm ocean temperatures and require minimal wind shear (change in wind speed or direction with height) to develop and strengthen.

Hurricane season and the Lone Star State’s 367 miles of open Gulf of Mexico shoreline make it a prime target for severe weather events.

“Texas leads the nation in both the most frequent severe weather events and the most expensive, accounting for 15 percent of all U.S. billion-dollar disasters. From 1980-2024, Texas experienced 171 billion-dollar weather and climate disaster events. Compared to its closest rival, Louisiana, Texas had 77 percent more billion-dollar weather events. Comparatively since 1980, Louisiana had 97 severe weather events and Florida was third with 84,” reported the nonprofit Texas 2036.

A breakdown of the types of severe weather events by category reveals Texas is affected the most by severe storms, drought, and cyclones. Out of the total 171 billion-dollar disasters in Texas, there were:

• 111 severe storms (64.9%)
• 19 droughts and heat waves (11.1%)
• 14 tropical cyclones, (8.2%)
• 10 winter storms (5.8%)
• 9 floods (5.3%)
• 7 wildfires (4.1%)
• 1 freeze (0.6%)

Understanding El Niño and La Niña

El Niño and La Niña are opposite phases of a naturally occurring climate pattern called the El Niño-Southern Oscillation (ENSO).

“During normal conditions in the Pacific Ocean, trade winds blow west along the equator, taking warm water from South America towards Asia. To replace that warm water, cold water rises from the depths — a process called upwelling. El Niño and La Niña are two opposing climate patterns that break these normal conditions,” says the National Oceanic and Atmospheric Administration (NOAA).

NOAA says that El Niño and La Niña can both have global impacts on weather, wildfires, ecosystems, and economies:

• El Niño: During El Niño, trade winds weaken. Warm water is pushed back east, toward the west coast of the Americas. El Niño can affect our weather significantly. The warmer waters cause the Pacific jet stream to move south of its neutral position. With this shift, areas in the northern U.S. and Canada are dryer and warmer than usual. But in the U.S. Gulf Coast and Southeast, these periods are wetter than usual and have increased flooding.
• La Niña: La Niña has the opposite effect of El Niño. During La Niña events, trade winds are even stronger than usual, pushing more warm water toward Asia. Off the west coast of the Americas, upwelling increases, bringing cold, nutrient-rich water to the surface. These cold waters in the Pacific push the jet stream northward. This tends to lead to drought in the southern U.S. and heavy rains and flooding in the Pacific Northwest and Canada. During a La Niña year, winter temperatures are warmer than normal in the South and cooler than normal in the North. La Niña can also lead to a more severe hurricane season.

What’s in the names? According to NOAA, El Niño means Little Boy in Spanish. South American fishermen first noticed periods of unusually warm water in the Pacific Ocean in the 1600s. The full name they used was El Niño de Navidad because El Niño typically peaks around December and Christmastime.

NOAA says that La Niña means Little Girl in Spanish. La Niña is also sometimes called El Viejo, anti-El Niño, or simply "a cold event."

“Episodes of El Niño and La Niña typically last nine to 12 months but can sometimes last for years. El Niño and La Niña events occur every two to seven years, on average, but they don’t occur on a regular schedule. Generally, El Niño occurs more frequently than La Niña,” explains NOAA.

Impact on U.S. Hurricane Season

The presence of El Niño or La Niña can significantly impact the severity and frequency of hurricanes during the U.S. hurricane season. Here's a more detailed breakdown:

• El Niño years: While El Niño can lead to fewer Atlantic hurricanes overall, the storms that do form can be more powerful due to the potential for rapid intensification. Additionally, El Niño can sometimes shift hurricane tracks southward, bringing a greater threat to Central America and the Caribbean.
  
  
• La Niña years: La Niña years often experience more frequent and intense hurricanes in the Atlantic basin, as the reduced wind shear allows storms to develop and strengthen more easily. La Niña can also lead to more storms tracking toward the U.S. coastline, particularly the East Coast and Gulf Coast.
  
  

“Simply put, El Niño favors stronger hurricane activity in the central and eastern Pacific basins and suppresses it in the Atlantic basin. Conversely, La Niña suppresses hurricane activity in the central and eastern Pacific basins and enhances it in the Atlantic basin,” explains NOAA.

Predictions for the 2024 Hurricane Season

As of June 12, 2024, the latest forecasts from NOAA's Climate Prediction Center (CPC) indicate a weak La Niña pattern is expected to persist throughout the 2024 Atlantic hurricane season.

A weak La Niña generally translates to above-normal hurricane activity in the Atlantic. This means we can expect a higher number of named storms (storms with sustained winds exceeding 39 mph), hurricanes (storms with sustained winds exceeding 74 mph), and potentially major hurricanes (Category 3 or higher on the Saffir-Simpson Hurricane Wind Scale) compared to an average season.

“A rough hurricane season is predicted this year,” reported the Corpus Christi Caller-Times. “NOAA predicted between 17 and 25 named storms this season, with eight to 13 becoming hurricanes, with winds of 74 mph or higher. Forecasters also expect between four and seven major hurricanes, classified as Category 3, 4, or 5, with winds of 111 mph or higher.”

However, it's crucial to remember that long-range hurricane predictions are not set in stone. Weather patterns can evolve throughout the season, and factors beyond ENSO, such as sea surface temperatures and atmospheric conditions, can also influence hurricane formation.

Staying Prepared

Regardless of the ENSO phase, it is always important for residents in hurricane-prone areas to stay informed, prepared, and ready to act on the advice of local authorities.

Here are some steps you can take to prepare for the 2024 hurricane season:

• Develop a Hurricane Plan: Discuss evacuation routes, sheltering options, and communication strategies with your family.
  
  
• Assemble an Emergency Kit: This should include non-perishable food, water, first-aid supplies, medications, flashlights, and a battery-powered radio.
  
  
• Stay Informed: Monitor weather reports closely throughout the season and pay close attention to advisories issued by the National Hurricane Center (NHC).
  
  
• Consider Flood Insurance: If you live in a flood-prone area, consider purchasing flood insurance to protect your property.
  
  

By understanding the influence of El Niño and La Niña on hurricane season and taking proactive steps to prepare, we can better manage the risks associated with these powerful storms.