East Coast Jellyfish Blooms Surging This Summer

Beachgoers up and down the East Coast—from New England to the Carolinas—are seeing a surge in jellyfish this summer, with stings reported at far higher levels than in recent years.

In Delaware, lifeguards have recorded more than 1,200 stings so far in 2025, compared with fewer than 300 during the same period last summer. On one particularly rough day in July, nearly 100 stings were reported at a single beach, sending several people to first aid stations for treatment. Lifeguards now carry vinegar and baking soda solutions to help ease the pain for swimmers.

The most common culprits include lion’s mane jellyfish, whose tentacles can stretch close to 100 feet, as well as sea nettles and moon jellies. Experts say warmer-than-average ocean temperatures this year have created the perfect environment for jellyfish populations to thrive. As a result, more blooms are appearing closer to shore, where swimmers are most likely to encounter them.

While the stings are rarely life-threatening, officials warn that large swarms can overwhelm beach patrols and catch visitors by surprise. Sensitive individuals, including children and those with allergic reactions, are urged to take extra care when entering the water.