At Nuâ uanu Pali on Oahu , the rain reached 10.25 inches ( 260.4 mm ) . The rain was so heavy that 4.11 inches ( 104 mm ) fell in one hour . At Nuâ uanu Pali on Oahu , a gauge recorded a total precipitation of 10.25 inches ( 260.4 mm ) ; the gauge also reported 1.6 inches ( 40 mm ) in 15 minutes , as well as 4.11 inches ( 104 mm ) in one hour .