El Niño has officially begun. Here's what that means for the U.S.

El Niño is officially here, and that means things are about to get even hotter. The natural climate phenomenon is marked by warmer ocean temperatures in the equatorial Pacific, which drives hotter weather around the world.

"[El Niño] could lead to new records for temperatures," says Michelle L'Heureux, a climate scientist at the National Oceanic and Atmospheric Administration's Climate Prediction Center.

The hottest years on record tend to happen during El Niño. It's one of the most obvious ways that El Niño, which is a natural climate pattern, exacerbates the effects of climate change, which is caused by humans burning fossil fuels and releasing greenhouse gasses into the atmosphere.

But temperature superlatives obscure the bigger trend: the last 8 years were the hottest ever recorded, despite a persistent La Niña that took hold in late 2020 and only just ended, depressing global temperatures. That's how powerful human-caused warming is: it blows Earth's natural temperature variability out of the water.

El Niño also exacerbates other effects of climate change. In the Northern United States and Canada, El Niño generally brings drier, warmer weather. That's bad news for Canada, which already had an abnormally hot Spring, and is grappling with widespread wildfires from Alberta all the way to the Maritimes in the East.

In the Southern U.S., where climate change is making dangerously heavy rain storms more common, El Niño adds even more juice. That's bad news for communities where flash floods have destroyed homes and even killed people in recent years, and where drain pipes and stormwater infrastructure is not built to handle the enormous amounts of rain that now regularly fall in short periods of time.

The one silver lining for U.S. residents? El Niño is not good for Atlantic hurricanes. Generally, there are fewer storms during El Niño years, because wind conditions are bad for hurricane development.

But, even there, human-caused climate change is making itself felt. The water in the Atlantic is very warm because of climate disruption, and warm water helps hurricanes grow. As a result, this year's hurricane forecast isn't the quiet one you might expect for an El Niño year. Instead, forecasters expect a slightly above-average number of storms.