Honolulu, Hawaii: High Surf Advisory as North Shore Surf Peaks at 18 to 24 Feet

Big surf is building along Hawaii's north shores on Wednesday night, and forecasters in Honolulu, Hawaii, say the largest waves will arrive late tonight and early Thursday. The National Weather Service in Honolulu kept a High Surf Advisory in effect until 6 p.m. Hawaii time on Thursday for the north and west facing shores of Niihau, Kauai, Oahu and Molokai, and for the north facing shores of Maui.

For north facing shores, the weather service expects surf to keep rising through the evening and peak at 18 to 24 feet late tonight and Thursday morning, close to warning level, before easing through Thursday. Surf should fall below advisory levels by Thursday night. For west facing shores, surf will peak at 14 to 18 feet late tonight, then ease through Thursday.

Warnings on the water and on land

The advisory covers the Oahu North Shore, the Waianae Coast, Kauai North and the north facing shores of Maui and Molokai. The weather service said strong breaking waves and strong currents will make swimming dangerous, and it told beachgoers to heed all advice from ocean safety officials. Its guidance was short: when in doubt, do not go out.

A Gale Warning also remains in effect until 6 a.m. Hawaii time on Thursday for Maalaea Bay, the Pailolo Channel, the Alenuihaha Channel and the Big Island leeward and southeast waters. Forecasters expect northeast winds of 25 to 35 knots with gusts up to 45 knots, and seas up to 14 feet. Winds that strong can capsize or damage vessels, the weather service said, and it urged mariners without the right experience and equipment to seek safe harbor before gale conditions arrive.

Small craft and wind advisories run into Thursday

A Small Craft Advisory is in effect until 6 p.m. Hawaii time on Thursday for the waters around Kauai, Oahu, the Kaiwi Channel, Maui County and the Big Island windward waters. Northeast winds up to 25 knots, gusts up to 35 knots and seas up to 14 feet will make conditions hazardous for small craft, and the weather service told inexperienced mariners to stay off the water.

On land, a Wind Advisory remains in effect until 6 a.m. Hawaii time on Thursday for parts of Kahoolawe, Lanai, Maui, Molokai and the Big Island. Northeast winds of 20 to 30 miles per hour with gusts up to 50 miles per hour can tear off shingles, knock down tree branches, blow away tents and awnings and make steering hard, above all for drivers of high profile vehicles. The weather service told residents to watch for falling branches, secure tents and awnings, and be ready for power outages.

The Honolulu Star-Advertiser reported the same set of alerts on Wednesday, with a gale warning, a wind advisory and a high surf advisory in effect for parts of the state. All of the advisories come from the trade wind pattern driving the surf, and the roughest conditions on Oahu's north shore are still ahead overnight.