Jellyfish Plague Beaches Across East Coast in Summer 2025

As the summer of 2025 winds down, beachgoers from Maine to Florida are facing an unwelcome nuisance: an influx of stinging jellyfish. According to experts, this year has seen a significant increase in jellyfish populations and stings along the East Coast.

At Delaware's Lewes Beach, Beach Patrol Captain Strohm Edwards reports that he has seen more jellyfish this year than ever before, with stings tripling. Further north, researchers believe massive groups of unusually large moon jellyfish, a species long thought to be harmless, have been stinging many swimmers in nearby Cape Cod towns. And on Florida's Daytona Beach, nearly 350 people were stung by jellyfish over the Memorial Day weekend.

Experts attribute this surge in jellyfish to a combination of warming waters and human activity, which have helped boost their populations. Jellyfish blooms can occur when large numbers spawn or are swept into an area by winds and tides, and their numbers tend to ebb and flow in roughly 20-year cycles.

As the summer comes to a close, beachgoers can expect to see different species of jellyfish appear along the East Coast. The Gulf Stream may carry Portuguese man o' wars from the tropics, while box jellyfish may arrive from the Caribbean. And in the waters around Massachusetts and Maine, large lion's mane jellyfish are fairly common towards the end of the summer.