After drenching Puerto Rico, Hurricane Ernesto strengthens in the Atlantic

After knocking out power for hundreds of thousands of people in Puerto Rico, Hurricane Ernesto was strengthening in the western Atlantic on Wednesday, leading to a hurricane watch in Bermuda.

Ernesto became a Category 1 hurricane on Wednesday, which means it has sustained wind speeds of at least 74 mph, and reached 80 mph Wednesday night. Ernesto was expected to continue strengthening this week, and could become a major hurricane by Friday, according to the National Weather Service.

A hurricane watch was issued for Bermuda, where hurricane conditions are possible by Saturday, the weather service said. The storm was not expected to approach the mainland United States, but forecasters warned it could cause life-threatening surf and rip currents along the East Coast by Thursday.

President Joe Biden approved a declaration of emergency in Puerto Rico, where nearly half of the customers served by the island’s utility were without power Wednesday. The power was also out for parts of the U.S. Virgin Islands.

Up to 10 inches of rain fell in some parts of Puerto Rico by midday Wednesday, the weather service said. On Wednesday evening, Luma Energy, which transmits and distributes electricity in the territory, reported that 570,000 customers were still without power there.

Bermuda was bracing for up to 9 inches of rain in some areas.

Daryl Jaschen, the emergency management director for the U.S. Virgin Islands, which are east of Puerto Rico, said in a briefing late Wednesday morning that the power was out across the entirety of St. John and St. Croix. There was some power being generated in St. Thomas, he said.

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Forecasters have warned that the 2024 Atlantic hurricane season could be much more active than usual.

Alberto, the first named storm of the Atlantic hurricane season, made landfall on the northeastern coast of Mexico as a tropical storm June 20, unleashing heavy rain, flooding and gusty winds. At least four people died in events related to the storm.

Beryl formed a little over a week later, on June 28, and became the earliest Category 5 hurricane on record. It carved a path of destruction through the Caribbean before crossing into the Gulf of Mexico and hitting the Texas coast.

Earlier this month, the National Oceanic and Atmospheric Administration continued its forecast of 17 to 24 named storms this year, an “above-normal” number and a prediction in line with more than a dozen forecasts earlier in the year from experts at universities, private companies and government agencies. Hurricane seasons produce 14 named storms on average from June 1 through Nov. 30.

The seasonal hurricane outlooks were notably aggressive because forecasters looking at the start of the season saw a combination of circumstances that didn’t exist in records dating back to the mid-1800s: record warm water temperatures in the Atlantic Ocean and the potential formation of the weather pattern known as La Nina.

La Nina occurs in the Pacific because of changing ocean temperatures, and it affects weather patterns globally. When it is strong, it typically provides a calm environment in the Atlantic; this allows storms to develop more easily and to strengthen without interference from wind patterns that might otherwise keep them from organizing.

This article originally appeared in The New York Times.