Expect rainy, muggy weather  with the chance of heavy showers and vog this weekend as today’s sunny skies turn cloudy and winds shift to the southeast, the National Weather Service said.

An area of enhanced moisture is moving over Hawaii Island today and will gradually move over the other islands over the next few days.

The National Weather Service posted a flash flood watch for the Big Island because of the possibility of heavy rain there through late Thursday night. Forecasters say the moist atmospheric conditions will remain over Hawaii island through Thursday, with the greatest potential for heavy rain in the Kau, Puna and Hilo Districts.

A winter weather advisory is also posted for the summits of Mauna Kea and Mauna Loa because of the potential for freezing rain above 12,000 feet through noon Friday.

Most of the rain will fall on windward areas of Oahu and Kauai tthrough Thursday, with some showers being blown over to leeward areas.

But winds will shift to the south over Kauai and Oahu this weekend, bringing muggy conditions, the possibility of voggy skies and the potential for heavy rain to leeward areas, starting Friday night.

Meanwhile, the National Weather Service also posted a high surf advisory for north and west shores of Niihau and Kauai and east shores of Hawaii island. Forecasters said a buoy northeast of Hawaii indicates a higher northwest swell than original forecasts. 

On the Big Island, a tradewind swell continued to generate 5- to 8-foot surf. Surf on Kauai and Niihau is expected to be 12 to 16 feet along north and west shores.

The advisory is in effect until 6 a.m. Friday for the Big Island and noon Thursday for Kauai County.

The forecast for Honolulu and south shores of Oahu calls for east winds, gusting to 30 mph this afternoon and mostly sunny skies through Thursday.

Skies will start to turn cloudy Thursday night into Friday and winds are expected to shift to the southeast by Friday night, bringing an increased chance of rain, humidity and hazy skies into at least Monday.