(BIVN) – High surf advisory in effect until 6 pm HST on Saturday.

The National Weather Service in Honolulu says surf is expected to build through the day today along south facing shores and reach advisory levels Thursday afternoon, as a long-period south swell fills in. The forecasters say the advisory-level surf is expected to continue through Saturday before trending down Sunday into early next week.

Wave heights along south facing shores of all islands will be 4 to 7 feet high this morning, rising to 6 to 9 feet this afternoon. The surf will gradually lower Sunday into early next week.

The National Weather Service says we can expect strong breaking waves, shore break, and strong longshore and rip currents making swimming difficult and dangerous.

“Currents make entering the water very hazardous,” a morning alert reads. “Beachgoers, swimmers and surfers should heed all advice given by ocean safety officials and exercise caution.”