It looks as if it's going to be a wet and muggy weekend for many Island residents.

The National Weather Service yesterday issued a flash flood watch for Kaua'i, O'ahu and Ni'ihau as a cold front and loss of the trade winds are expected to bring heavy showers and possible thunderstorms. The watch is in effect from late tonight through tomorrow evening.

Lead forecaster Jeff Powell said the winds were forecast to gradually shift last night.

"When the winds turn southeasterly and you get weak flow, you bring moisture up," Powell said. "It will be wet."

Along with the rain, the wind shift also will mean muggy conditions through the weekend, he said. Vog also may increase until the trade winds blow the haze away early next week.

A flash flood watch means that conditions may develop that lead to flash flooding. Residents are asked to be prepared to take action should a flash flood warning be issued.

In addition to the rain, a small craft advisory is in effect for Hawaiian waters through early this morning.