The National Weather Service in Honolulu has placed Kauai and Niihau under a flash flood watch from this evening through late Tuesday night.

The weather service said today that “deep tropical moisture along and ahead of an approaching front will bring the potential for heavy rainfall, thunderstorms and flash flooding to Kauai.”

Forecasters warned of heavy rainfall that could make some roads dangerous and impassible due to severe runoff. “Debris in streams and gulches could clog bridges and culverts resulting in dangerous flooding. Isolated landslides could also occur,” they said.

The forecast for the rest of the state calls for muggy conditions today and through much of the week with light southerly winds. A more typical trade wind pattern may return at the end of the week, the weather service said.

Honolulu can expect possible showers Tuesday and Wednesday, with highs in the upper 80s.