UPDATE: THURSDAY 5:35 a.m.

The National Weather Service in Honolulu this morning extended the high surf warning for most Hawaiian islands until 6 a.m. Friday.

The warning is in effect for north and west shores of Niihau, Kauai, Oahu and Molokai; north shores of Maui, and west shores of Hawaii island.

Forecasters expect waves of 25 to 35 feet along north shores; 18 to 24 feet along west shores of the smaller islands; and 12 to 16 feet along west shores of the Big Island today. Surf will gradually diminish tonight, they predict.

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Beachgoers should expect “very strong breaking waves and powerful longshore and rip currents … ocean water surging and sweeping across beaches, with localized beach erosion,” the warning says.

In addition, a high surf advisory is in effect for west shores of Maui and Lanai, and north shores of the Big Island

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The largest swell of the season is here — and is expected to peak Wednesday, bringing surf up to 50 feet to north shores.

The National Weather Service’s high surf warning covers the north and west-facing shores of Niihau, Kauai, Oahu, and Molokai; the north-facing shores of Maui; and the west-facing shores of Hawaii island through 6 p.m. Thursday.

Forecasters expect the northwest swell is expected to build down the island chain and peak today, then gradually lower through the day Thursday after shifting out of the north-northwest late tonight.

Officials say the public should stay away from the shoreline along affected coasts and postpone entering or leaving channels affected by the high surf.

Surf is expected to reach 40 to 50 feet along north facing shores, and 25 to 35 feet along west facing shores today.

In addition to powerful rip currents, ocean water is expected to surge and sweep across beaches, periodically over-topping vulnerable coastal roadways, with localized beach erosion.

Wave run-up is also expected to impact coastal properties and infrastructure, especially around high tide just before daybreak.

A high surf advisory, meanwhile, is in place for the west-facing shores of Maui and Lanai, and the north-facing shores of Hawaii island due to the swell, also through 6 p.m. Thursday.

Strong, breaking waves and currents in these areas will make swimming dangerous today through Thursday evening. The public should heed all advice from ocean safety officials.

Surf will remain stable along south shores, at 1 to 3 feet, and at east shores, at 2 to 4 feet, today and Thursday.

A small craft advisory is also in effect for leeward Maui County waters, Hawaii island waters and several channels, through 6 p.m. Thursday.