UPDATE: 5:45 p.m.
A high surf warning that was scheduled to expire Thursday morning has been extended until 6 p.m. Friday as a second, larger northwest swell approaches the islands, forecasters said this evening.
The new warning covers north and west shores from Niihau to Molokai, and north shores of Maui, the National Weather Service said.
Surf of 20 to 25 feet is expected to rise to 30 to 40 feet Thursday afternoon and night along north shores, while west shores will see wave climb from 14 to 20 feet rising to 18 to 25 feet, forecasters said.
“The current northwest swell should slightly decrease tonight and may briefly drop below warning levels during this time, but a larger northwest swell will be moving down the island chain Thursday into Thursday night,” the latest high surf warning said. “This should result in surf exceeding well above warning thresholds by sunset on New Years Eve.”
Forecasters expect the swell is to peak Thursday night, then decline Friday and Saturday.
Impacts from the high surf include ocean water occasionally sweeping across portions of beaches, and strong longshore and rip currents. “Breaking waves may occasionally impact harbors making navigating the harbor channel dangerous,” forecasters said.
Surf up to 30 feet along north shores and 20 feet along west shores for Kauai County and Oahu has prompted a high surf warning, in effect through 6 a.m. Thursday.
The National Weather Service issued the high surf warning for the north and west shores of Niihau, Kauai and Oahu after an uptick detected at the Waimea Buoy this morning.
Surf of 20 to 30 feet is expected along north shores, while surf of 12 to 20 feet is expected along west shores today.
In addition to large, breaking surf, weather officials warn of dangerous currents, shorebreak and ocean water that will occasionally sweep across portions of beaches. Entering the water is very hazardous under these conditions.
“Anyone entering the water could face significant injury or death,” officials said.
Surf for other shores remain below advisory levels — 4 to 6 feet today for east shores, which is expected to rise to 6 to 8 feet by Thursday evening due to strengthening trades.
Surf on south shores remains at 1 to 3 feet today through Thursday.
Forecasters said another similar-sized, northwest swell is expected to arrive Thursday and continue into Friday before surf trends down again over the weekend.
Trades are expected to return this afternoon, strengthen tonight and become breezy to locally windy on New Year’s Eve Thursday through Saturday.
Today’s forecast is partly cloudy for the windward side, mostly sunny for the leeward side for the smaller isles, with highs from 79 to 84 degrees Fahrenheit and fairly dry conditions for the entire island chain. Temperatures tonight drop to 66 to 71 degrees.
Trades remain at 15 to 20 mph today through tonight, and increase up to 30 mph on Thursday through the weekend.
Bands of moisture will move through the islands as trades pick up, favoring windward and mauka areas and reaching the leeward side at times. Forecasters said no significant rainfall, however, is expected during the next seven days.
Another record high, meanwhile, was set in Kahului on Tuesday. A record high of 90 was set at Kahului, surpassing the previous record of 87 set for that day in 2019. It was the fifth record high set for Kahului this month, in addition to several record high matches.
A small craft advisory has also been issued for Maalaea Bay, Pailolo Channel, and Hawaii island leeward and southeast waters, effective through 6 a.m. Friday.