Update: High surf advisory extended as overlapping northwest swells head toward peak

Update at 4:09 p.m. Dec. 9 (updated at 7:14 a.m. Dec. 10 with corrected information from the National Weather Service in Honolulu): A high surf advisory for west- and north-facing shores of Ni‘ihau and Kaua‘i was extended through 6 a.m. Wednesday.

A pair of overlapping northwest swells will peak late this afternoon or early evening before gradually declining to seasonal norms by Thursday, and the National Weather Service forecast office in Honolulu expects surf along those coasts to remain above advisory levels through the day and overnight.

Surf of 18 to 24 feet is expected today, falling to 12 to16 feet tonight, along the northern shorelines of both islands. Western shorelines will see surf of 14 to 18 feet today, falling to 9 to 14 feet tonight.

Strong breaking waves and strong currents will make swimming and other ocean activities in the advisory areas dangerous.

The public is advised to heed all advice from ocean safety officials — when in doubt, don’t go out.

The overlapping north-northwest swells will also elevate seas to at least 10 feet across all coastal waters by this evening.

Original post: A high surf advisory is in effect until 6 p.m. Tuesday for the north- and west-facing Ni’ihau and Kaua’i shores.

According to the National Weather Service in Honolulu, surf will increase throughout the day as a fresh north-northwest (330-340 degrees) swell builds down the island chain. This trend is expected to continue, with a peak likely occurring tonight through Tuesday.

The advisory will likely need to be expanded down the island chain later today.

Surf is expected to build to 10 to 15 feet by this afternoon. Strong breaking waves and currents will make swimming dangerous.