Swarms of nomad jellyfish (Rhopilema nomadica) have been reported on Israeli beaches and off the Mediterranean coast, primarily in the north. The jellyfish have a diameter of 70 centimeters, more than two feet.
A similar phenomenon was observed two years ago. They arrived before last weekend's storm and are expected to stay between one and three months. Researchers noted that no jellyfish were sighted during 2016. While more research is needed, one theory says the effect of global warming on the Mediterranean has made it too hot during the summer.