Kahului and Hilo harbors may experience moderate to strong surges this weekend because of a long-period swell that was building Friday night and was expected to peak today, the National Weather Service said.

The swell will affect harbors that are exposed to the north, and bring the threat of waves breaking near harbor entrances, the weather service said. Mariners were advised to use caution when entering or leaving port, or when mooring or launching vessels.

Meanwhile, a high-surf advisory for east-facing shores of the Hawaiian Islands that had been in effect until 6 a.m. Sunday was canceled after surf subsided to below 8 feet, the weather service said.