Their stings could prove to be deadly for some, and they're showing up at Westchester beaches earlier than before.

Signs are posted at the entrance of Rye Beach warning bathers about a jellyfish increase. Normally, the sticky water dwellers don't make their first appearance until late July, but they began showing up in large numbers about two weeks ago.

Officials blame the early arrival on favorable temperatures and water currents. Rye Beach officials say out of the thousands of bathers who packed the water last weekend, only two were stung. They were treated at first aid stations.

While some jellyfish stings are only as bad as a mosquito bite, others can pack quite a punch, and some can cause death for people who are allergic.

Lion's mane jellyfish were blamed for stinging athletes who jumped into the Hudson River on Sunday during the swimming stage of the New York City Triathlon. One athlete died after being pulled from the water. An autopsy failed to determine the cause of death.