The National Weather Service issued a flood advisory for the island of Oahu at 9:15 p.m. Tuesday evening.
The advisory was in effect until 12:15 a.m.
Radar showed pockets of heavy rain moving across the Koolau mountains at about 1 inch an hour, forecasters said.
The advisory covers Honolulu, Maunawili, Waimanalo, Waikane, Waiahole, Kahaluu and Kaneohe.
Rainfall and runoff will also cause hazardus driving conditions including reduced visibility and poor braking action due to ponding.
Officials are warning the public to stay away from streams, drainage ditches and low lying areas prone to flooding.