An area of very moist air has spread over the islands and a trough aloft is making the atmosphere unstable.
The combination of moisture and instability will bring a chance of flooding rains.
The chance of flooding will be greatest from Oahu to the Big Island.
Earlier Friday afternoon, a flash flood warning was in effect as radar indicated heavy rain near Waimalu, falling at a rate of over 2 inches per hour.
Heavy rain triggered ponding on the H-1 Freeway, especially near the Kaahumanu Street overpass, where traffic came to a halt as drivers attempted to navigate high water levels on the road.
All islands remain under a flash flood watch through Saturday night as a moist, unstable atmosphere brings heavy rain to parts of the state.
Drier, cooler weather is expected late Sunday through much of next week.