Update Thursday 5:15 a.m.

A flash flood watch for all islands has been extended through this afternoon.

“Flash flooding potential will remain high due to a combination of an upper disturbance over the region and plenty of lingering moisture and instability,” the National Weather Service said in an alert.

Update 9:30 p.m.

More rain is expected for Oahu and possibly Kauai on Thursday as a band of moisture was moving northwards over the islands.

“Unsettled weather, with heavy rain and thunderstorms, will prevail through Thursday,” the National Weather Service said.

However, conditions were expected to improve for the weekend with light winds, but possibly humid conditions, the weather service said.

Tonight, a flash flood watch remained in effect for the entire state.

In addition, a large northwest swell was spreading down the island chain.

Forecasters issued a high surf warning that was in effect until 6 p.m. Thursday for north- and west-facing shores of Niihau, Kauai, Oahu, and Molokai, and north-facing shores of Maui with surf of 25 to 30 feet. The surf was expected to decrease to 20 to 25 feet Thursday.

A high surf advisory was in effect for the northern shores of Hawaii island through 6 p.m. Thursday with surf reaching 10 to 15 feet.

A high wind warning and a winter storm warning also were in effect until 6 p.m. Thursday for Big Island summits.

Winds were forecast to be 30 to 50 mph with 70 mph gusts. Delay travel to the summit areas until the winds subside, the weather service said.

The winter storm warning said snowfall of three to six inches was possible with poor visibility and icy roads.

Update 6 p.m.

The National Weather Service has issued a flood advisory for Maui until 8:45 p.m. and a winter storm warning for the Big Island summits until Thursday evening.

“At 5:43 p.m., radar indicated that rainfall has temporarily decreased across windward east Maui, though streams remain elevated. Additional heavy showers are expected to redevelop into the evening,” the flood advisory said.

The advisory covers Haiku-Pauwela, Pauwela, Huelo, Nahiku, Kipahulu, Hana, Kailua, Wailua and Haleakala National Park.

The winter storm warning is in effect until 6 p.m. Thursday for summits above 12,000 feet. Forecasters said up to 6 inches of snow is possible and southwest winds from 30 to 50 mph, with gusts up to 70 mph. A high wind warning is also in effect for the area for the same time period.

The entire state remains under a flash flood watch through late tonight. The heavy-rain threat was concentrated near Maui and the Big Island, but “this band is expected to move north tonight, potentially shifting the threat of heavy rain to Kauai and Oahu,” forecasters said.

Also, a high surf warning is in effect until 6 p.m. Thursday for north- and west-facing shores of Niihau, Kauai, Oahu and Molokai, and northern shores of Maui with waves up to 30 feet, decreasing to 20 to 25 feet on Thursday. Northern shores of the Hawaii island are under a high surf advisory, with waves up to 15 feet.

Update 12 p.m.

A high surf warning is in effect for most islands and weather officials expect surf to be even bigger than originally forecast.

The affected areas remain the same, except for the addition of the west-facing shores of Oahu, but surf up to 25 to 30 is expected today.

Also, a high surf advisory is scheduled to go into effect at 6 p.m. for the north and east shores of Hawaii island. Surf in those areas is expected to reach 10 to 15 feet.

The advisory is scheduled to expire at 6 a.m. Thursday.

Update Wednesday 5:00 a.m.

A flash flood watch remained in effect through late tonight, the National Weather Service said.

Locally heavy showers and thunderstorms could develop throughout the islands today as a band of moisture stalled over Maui and Hawaii island moves north over the rest of the islands later today, forecasters said.

A high surf warning for most islands is scheduled to take effect at 10 a.m. today and is scheduled through 6 a.m. Thursday.

Weather officials expect surf to peak at up to 20 to 25 feet in warning areas.

Affected areas include the north and west shores of Niihau, Kauai and Molokai and north shores of Oahu and Maui.

Update 7:30 p.m.

The state remained under a flash flood watch through late Wednesday night, the National Weather Service said.

A flash flood warning for Maui expired at 7:30 p.m.

While heavy showers could develop over all the islands, the main threat for heavy rain will be along a band of moisture stalled over Maui and the northern part of Hawaii island, the weather service said.

That band could drift northward tonight.

The weather service warned that heavy downpours could lead streams to quickly overflow and cause life-threatening flash flooding.

Update 5 p.m.

The island of Maui is under a flash flood warning until 7:30 p.m., forecasters said.

The warning includes, but is not limited to, Kahului, Kihei, Waikapu, Maalaea, Pauwela, Wailea, Huelo, Paia, Makawao, Puunene, Kula and Waiehu.

“At 4:37 p.m., flooding from Kulanihakoi Gulch has closed South Kihei Road between Kaonoulu and Kulanihakoi Street,” the warning from the National Weather Service said. “Heavy rainfall is also moving over the leeward Haleakala slopes from the southwest. This rainfall can produce flash flooding in normally dry gulches from Makena to Kihei and in the Keokea and Kula areas of Upcountry Maui.”

Maui Police said this afternoon that sections of South Kihei Road were closed due to flooding, with water up to 2 feet deep in some areas.

The entire state is under a flash flood watch until Wednesday night.

Update 4:10 p.m.

The entire state is under a flash flood watch until late Wednesday night, forecasters at the National Weather Service in Honolulu said this afternoon.

“While isolated heavy showers could develop over all islands, the main threat for heavy showers and thunderstorms will be along a band of moisture currently stalled over Maui and northern Big Island. This band may drift northward on Wednesday night,” the advisory said.

East Maui also remains under a more-immediate flood advisory.

Maui Police said this afternoon that sections of South Kihei Road were closed due to flooding, with water up to 2 feet deep in some areas.

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The National Weather Service in Honolulu has issued a flood advisory for East Maui this afternoon.

The advisory, which is in effect until 5:15 p.m., includes Kahului, Kihei, Pauwela, Wailea, Huelo, Paia, Makawao, Puunene, Kula, Pukalani, Haliimaile and Ulupalakua.

“At 2:20 p.m., radar indicated areas of heavy showers and thunderstorms along both windward and leeward slopes of Haleakala. The heaviest showers were producing rain rates in excess of 2 inches per hour,” the advisory said. “Expect continued areas of heavy showers and possible rises in streams through the afternoon.”

Forecasters said the advisory maybe extended if heavy rain persists.

The weather service also issued a wind advisory for Big Island summits until 6 p.m. Wednesday, saying southwest winds as high as 50 mph are expected. “Motorists, especially those in high profile vehicles, are urged to drive with extra caution,” the advisory said.