A Halloween swell has prompted a high surf advisory for the north shores of Oahu, Kauai, Molokai and Niihau, prompting the National Weather Service to issue a high surf advisory through Friday.

The advisory began at midnight Wednesday and continues through 6 p.m. Friday.

Wave faces of 10 to 15 feet are expected. The advisory also covers the west shores of Kauai and Niihau.

The surf is expected to reach advisory levels by midnight and continue through this afternoon. The swell will drop slightly Thursday evening, before building quickly again tonight.

Forecasters warn beach-goers can expect strong, breaking waves and shore break. Strong currents can also make swimming difficult and dangerous.

Beach-goers should heed advice from lifeguards and exercise caution.

The swell was generagted by a low pressure system in the North Pacific.