Hong Kong's Leisure and Cultural Services Department announced on September 18 that red flags had been raised at five beaches because of big waves, according to the department's notice. The affected beaches were Stanley Main Beach, Shek O Beach and Big Wave Bay Beach in Southern District on Hong Kong Island, and Silverstrand Beach and Clear Water Bay Second Beach in Sai Kung District.

Beachgoers were advised not to swim at these beaches while the red flags were in place. The notice described the warning as a snapshot of conditions on that date, and did not say when the flags might be lowered.

The announcement was issued as a broadcast notice for television and radio announcers, asking them to relay the warning to swimmers as soon as possible.