The National Weather Service in Honolulu has issued a flash flood watch for all Hawaiian islands beginning Sunday.

The flash flood watch, which means conditions are favorable for flash flooding, is in effect from Sunday morning through late Monday night. It continues for Oahu, Hawaii island, Kauai, Maui, Lanai, Molokai, Niihau and Kahoolawe.

Heavy rain is expected to first materialize over Maui County and Hawaii island on Sunday then spread westward over the area through late Sunday and Monday nights.

“Flood prone roads and other low lying areas may be closed due to elevated runoff and overflowing streams. Urban areas may receive more significant flooding and property damage due to rapid runoff,” according to forecasters.

Forecasters warn that flash flooding is life threatening, so avoid crossing fast flowing water in your vehicle or on foot.