Honolulu lifeguards warn beachgoers of an influx of box jellyfish in waters on the south and east shores.

As of 10:45 a.m. today, lifeguards counted an estimated 920 jellyfish from Ala Moana Beach to Waikiki Beach and treated 13 beachgoers who suffered stings this morning, according to Shayne Enright, spokeswoman of the Emergency Medical Services Department.

At Hanauma Bay, lifeguards counted an estimated 10 jellyfish and treated 12 stings.

Signs were posted at affected beaches to warn beachgoers.

Box jellyfish usually arrive near shore 8 to 10 days after a full moon which was Feb. 10.