A high surf advisory for most north- and west-facing shores of Hawaii has been extended to 6 a.m. Wednesday.

The National Weather Service says a pair of overlapping, northwest swells will peak later today before gradually declining, and surf along north and west shores is expected to remain above advisory level through tonight.

>> Along the north-facing shores of Niihau, Kauai, Oahu, Molokai, and Maui, surf of 18 to 24 feet is expected today before falling to 12 to 16 feet tonight.

>> Along the west-facing shores of Niihau, Kauai, Oahu, and Molokai, surf of 14 to 18 feet is expected along west shores today before falling to 9 to 14 feet tonight.

Officials warn of strong, breaking waves and currents, which will make swimming dangerous.

“Heed all advice from ocean safety officials,” said the advisory. “When in doubt, don’t go out.”

A wind advisory also went into effect at 10 a.m. today for portions of Kahoolawe, Lanai, Maui, and Hawaii island, due to northeast winds of 20 to 30 mph, with gusts up to 50 mph, effective until 6 p.m. Wednesday.

Winds this strong can tear off shingles, knock down trees and make it difficult to steer, especially in high-profile vehicle, and those under the advisory should be prepared for power outages.

Additionally, forecasters say these strong trades and marginally dry conditions “warrant continued monitoring for potential fire weather conditions” on Wednesday and Thursday.

A small craft advisory for most Kauai waters, Maalaea Bay, Pailolo and Alenuihaha channels, and the leeward and southeast waters of Hawaii island also remains in effect until 6 p.m. Thursday.