May 6, 2025 - News

Miami beaches covered in seaweed as researchers forecast record sargassum season

Martin Vassolo

Swaths of sargassum, or seaweed, washed up in Key Biscayne on Thursday, April 24 and was raked into piles to be taken to the landfill. — Swaths of sargassum washed up in Key Biscayne on April 24 and was raked into piles to be taken to a landfill. Photo: Ashley Miznazi/The Miami Herald/Tribune News Service via Getty Images

Brown seaweed has already begun to wash up on Miami's beaches, but researchers predict a record amount of the stinky sargassum could still be on its way.

Why it matters: The seaweed provides essential habitat for ocean life, but it's a tourism turnoff once it hits the shore, producing a foul odor and sullying beachfront vistas.

Sargassum usually blooms from May to August across the Atlantic Ocean, per the South Florida Sun Sentinel.

Driving the news: The University of South Florida Optical Oceanography Lab, which tracks sargassum movement using satellite data, says 2025 will be a record year for sargassum.

There was an estimated 31 million tons of sargassum across the Atlantic Ocean, Caribbean Sea and the Gulf last month — 40% more than the previous high in June 2022, per USF research assistant professor Brian Barnes, co-author of the lab's April 30 report.

What's next: This month, more sargassum is expected to head to the west Caribbean Sea and the Gulf.

Florida's east coast and the Caribbean will continue to be inundated with sargassum, per the report.

The bottom line: Whether South Florida sees the worst of the sargassum bloom depends on the way the wind blows, per the Sun Sentinel.

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Miami beaches covered in seaweed as researchers forecast record sargassum season

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