El Niño is here, so what does it mean?

Forecasters are warning that a new El Niño weather pattern could bring strong impacts to areas around the world. In this 2024 photo, dramatically low water levels are seen in a reservoir feeding the Guavio Hydroelectric Power Plant in Gachalá, in Colombia's Guavio Province, during dry conditions linked to El Niño. Jhojan Hilarion/AFP via Getty Images hide caption

This summer was already predicted to be hot for much of the planet, after a near-record year of global heat last year. But El Niño — the influential weather pattern associated with heat, unlike the cooler La Niña — has arrived, and it's raising more alarm.

"If we have a big El Niño on top of the long-term warming trend, that just really enhances the probability that we'll see a new record global mean temperature," says meteorologist Nat Johnson of the National Oceanic and Atmospheric Administration, who is part of the El Niño forecasting team.

Officials from Europe to India and Australia are warning of potential harmful effects, including heat waves and abnormally dry conditions.

"Even though it's a phenomenon that's rooted in the tropical Pacific," Johnson says, global jet streams transfer El Niño's influence far and wide.

"Basically, every continent, you'll see some sort of impact from an El Niño or a La Niña event," he says. Some of that impact, he says, is economic, from disrupted marine ecosystems and fisheries.

"The strongest impacts initially will tend to be in the tropical regions," Johnson says, adding that El Niño tends to bring enhanced drought to a wide band of locations, from Indonesia to the northern Amazon.

"There is a 63% chance of a very strong El Niño [from November to January] that would rank among the largest El Niño events in the historical record going back to 1950," NOAA said in an advisory .