Abnormally hot temperatures in the Pacific Ocean have sparked questions about whether a “Super” El Niño cycle could bring extreme or erratic weather this year.
But El Niño does not guarantee any specific weather despite the hype, according to Dan McEvoy, a climatologist at the Desert Research Institute’s Western Regional Climate Center. The historical weather record has shown that, he said.
“There are still a lot of unknowns with the winter precipitation as well as temperatures,” McEvoy said. “There have been El Niños that have brought wet conditions, dry conditions and near-average conditions. It gets even murkier with strong events, because there’s only a handful of those to look at.”
Still, what could become the strongest El Niño on record has some observers hopeful for drought relief and rain in the driest major metropolitan area in the nation. Some evidence suggests that record-hot ocean temperatures that are driving the weather this year are a reflection of a changing climate, said Chad Merrill, a senior meteorologist at AccuWeather.
Scientists believe climate change generally means a higher probability of stronger El Niños in the future, Merrill said, though it remains an active area of research.
“Global warming is the warming of the ocean,” Merrill said. “When you get the right wind flow to bring that water from the West Pacific to the East Pacific, you can get these anomalies.”
What is an El Niño pattern, anyway?
El Niño is a naturally occurring climate pattern where the central and eastern tropical Pacific Ocean is warmer than normal. When those temperatures are cooler than normal, climatologists call it La Niña.
No specific scientific measure makes the phenomenon “super,” but this El Niño year is on track to be a significant anomaly, according to Columbia University’s International Research Institute for Climate and Society.
El Niño strength is commonly measured using the Niño-3.4 index, which tracks how much sea-surface temperatures in a region of the central and eastern tropical Pacific deviate from the historical average. Federal scientists classify an El Niño with an anomaly of 2 degrees Celsius as “very strong.”
As of mid-August, the latest weekly Niño-3.4 reading had reached 2.7 degrees Celsius above average — an anomaly equivalent to 4.9 degrees Fahrenheit — and forecasts call for the event to strengthen further in the coming months.
That makes it pretty “super.”
The impending Super El Niño has fit into promotions for the Lee Canyon resort on Mount Charleston, encouraging visitors to book their reservations early. The last El Niño season, which was moderate, brought 215 inches of snow to Lee Canyon in 2023-2024, up from its normal 129 inches, said general manager Josh Bean.
“Since no single climate pattern can tell us exactly what the season will bring, our focus is on being prepared for a range of conditions and ready to welcome guests back for winter,” Bean said in a statement.
One study published Thursday suggests the burning of fossil fuels and associated warming of the planet is tied to a 36 percent jump in the strength of El Niño since the mid-1800s. Greenhouse gas emissions over the last 40 years are linked to a 16 percent increase in strength, the study showed.
Lead author Julia Cole, a paleoclimate scientist at the University of Michigan, told The Associated Press that her lab studied 29 coral fossils in the Galapagos Islands from varying time periods, the oldest dating back to the year 1100.
“We found that the increase in El Niño’s strength closely parallels the rise in global temperature that is due to human causes such as the burning of fossil fuels,” Cole said.
Drought relief not a given, either
In broad strokes, El Niño years tend to bring more rain to the Las Vegas Valley and other parts of the American West.
Brian Planz, a meteorologist at the National Weather Service’s Las Vegas office, said it’s far too early to attribute any current weather conditions to El Niño. The historical weather record provides some clues.
“With an El Niño, wetter-than-normal precipitation is a possibility more so than with La Niña events,” Planz said. “But by no means does that guarantee it’s going to happen.”
According to Merrill, of AccuWeather, 2015 was the most recent El Niño year of comparable strength, bringing fall average temperatures to Las Vegas of 71.9 degrees and 1.42 inches of rain — the 10th warmest and 22nd wettest fall seasons.
That means the last strong El Niño did not deliver on its usual promise of rain for the Southwest.
Andrew Trelease, general manager and chief engineer of the Clark County Regional Flood Control District, said the region’s 722 miles of storm drains and channels along with 113 detention basins should afford the community some peace of mind if strong rains come.
“Thanks to the combination of robust infrastructure and an informed community, Southern Nevada is built to withstand heavy rain — whenever it may fall,” Trelease said in a statement.
The year 2023 was the most recent El Niño, with a moderate strength. But it brought the 16th wettest fall to Las Vegas with 1.72 inches of rain, Merrill said.
Merrill said he has hope for an above-average snow season in the Rocky Mountains, but he stressed that it’s too soon to have any reliable data to support that wish. Last season was abysmal for the Colorado River Basin, with runoff into Lake Powell, from the Rockies snowmelt, coming in at 13 percent of normal.
“The short-term drought will be helped quite a bit,” Merrill said. “The long-term drought will still be intact. It takes more than one season of above-average precipitation to actually see a dramatic improvement in the water supply.”
Contact Alan Halaly at ahalaly@reviewjournal.com. Follow @AlanHalaly on X. The Associated Press contributed to this report.
