Historic El Niño, Marine Heat Wave Forecast

A potentially historic El Niño is expected to bring significant changes to Southern California weather patterns and marine ecosystems later this year, federal and local experts announced at the Aquarium of the Pacific's Our Warming Waters press briefing.

Forecasters from the National Oceanic and Atmospheric Administration anticipate a transition to strong El Niño conditions by late summer, compounding a marine heat wave already present off the Southern California coast. The convergence of these warming ocean temperatures is projected to bring unusual ocean species to Long Beach shores.

Dr. Ariel Cohen, a meteorologist at the National Weather Service in Los Angeles, detailed the mechanics of the impending weather shift. Under normal conditions, trade winds push warm water westward across the Pacific.

During an El Niño, these winds slacken, allowing warm water to pool off the coast of the Americas. This shift alters the atmospheric jet stream, typically bringing uneasy weather and increased precipitation across the southern United States.

Cohen stated there is a 63 percent probability of a very strong El Niño developing between November and January. This event could rank among the most powerful recorded since 1950, mirroring the stronger cycles of 1997 to 1998 and 2015 to 2016.

While El Niño patterns generally tilt the odds toward wetter-than-normal conditions in Southern California, Cohen stated that actual outcomes can vary significantly. Even if precipitation levels remain relatively low, Long Beach and surrounding coastal communities could face hazards such as violent waves and powerful rip currents generated by distant storm systems over the Pacific Ocean.

Increased moisture from eastern Pacific tropical storms could raise the threat of heavy runoff and flash flooding. Residents living near recent wildfire burn scars face a particularly elevated risk of dangerous debris flows if heavy rain materializes over vulnerable terrain.

The early arrival of El Niño is also influencing hurricane forecasts. The pattern typically increases wind shear in the Atlantic basin, which can disrupt the formation of tropical storms. However, in the eastern Pacific, warm water provides the main factor for storm development.

A marine heat wave is currently underway along the Central American coastline, with sea surface temperatures significantly above historical averages. Experts note that this setup contributed to the rapid development of storms like Hurricane Hilary in 2023, which weakened to a tropical storm but still brought severe flooding and record-breaking rainfall to Southern California.

The arrival of El Niño will exacerbate an existing marine heat wave off the coast of Southern California that has persisted since late 2025. Dr. Andrew Leising, a research oceanographer at NOAA's Southwest Fisheries Science Center, noted that while the current warm water mass is only about a third of the size of the massive marine heat wave known as "The Blob" that disrupted Pacific ecosystems starting in 2014.

As ocean temperatures rise, Long Beach beachgoers can expect to see a shift in local marine life. Warm-water events typically lead to decreased upwelling, an oceanic process that brings cold, nutrient-rich water to the surface. This reduction reduces plankton populations, which form the foundational base of the marine food web.

Nate Jaros, vice president of animal care for fish and invertebrates at the Aquarium of the Pacific, explained that warmer waters will also attract tropical and warm subtropical species to the region. This shift may bring rare visitors to local waters, such as yellowfin tuna, mahi-mahi, yellow-bellied sea snakes, seahorses, and pelagic red crabs.

Jaros added that the public should anticipate an increase in shark sightings near the coast. Species such as mako, blue, and white sharks are drawn to the warmer currents, and shifting ocean conditions have already pushed some shark nursery areas farther north.

Additionally, prolonged heat threatens local habitats, such as kelp forests, which serve as essential nurseries and feeding grounds. Bull kelp habitats in California have experienced large declines during past marine heat waves. This habitat loss endangers other species that rely on the kelp ecosystem, including the endangered white abalone and the sunflower sea star.

The warming waters will also affect birds and marine mammals. Brett Long, the aquarium's vice president of animal care for birds and marine mammals, described how marine heat waves can lead to starvation for seabirds as their typical prey moves deeper into the ocean or farther offshore in search of cooler water.

Whales, including the blue whales frequently spotted off the Southern California coast, may also be forced to alter their behavior. As the krill they depend on becomes scarce, whales often move closer to shore, which increases their risk of entanglement in fishing gear and collisions with commercial ships.

An immediate concern for the upcoming months is the proliferation of harmful algal blooms. These toxic blooms thrive in warmer waters and produce dangerous neurotoxins. California sea lions serve as an important indicator species for these toxins.

Long stated that as sea lions consume contaminated fish, they can suffer severe neurological illness and death, leading to a marked increase in strandings along local beaches. Warmer temperatures also negatively impact sea lion productivity, often resulting in smaller, undernourished pups.

In response to these impending environmental challenges, the Aquarium of the Pacific is expanding its conservation efforts. Jeff Flocken, the aquarium's president and chief executive officer, emphasized the institution's commitment to providing a sanctuary for impacted wildlife.

The aquarium is preserving bull kelp genetic material in cold storage for future restoration projects. It runs community science programs to monitor plankton populations, enabling early detection of harmful algal blooms for swift local response.

To handle the expected increase in animal strandings, the aquarium has teamed up with local rescue centers through the Pinniped Patrol. This volunteer group educates the public and secures beaches when distressed sea lions wash ashore.

Additionally, the aquarium is launching a public service campaign this summer to share information about the marine mammal rescue hotline, so that Long Beach residents know how to report sick or injured animals.

For any inquiries or further information, please contact Jose Cervantes at JoseC.Press@pm.me