Heavy showers and possible thunderstorms will move from west to east ahead of an approaching cold front. A Flash Flood Watch is in effect for Niihau, Kauai and Oahu through Monday afternoon because of the threat of heavy rain. The watch will be expanded to include Maui County this evening. For the daytime hours at least, Maui County and the Big Island will have partly to mostly cloudy skies with spotty showers. Light south to southeast winds will continue to spread volcanic haze from the Big Island to the rest of the state.