A weather system north of the state is bringing moist air and locally heavy showers, as the National Weather Service extended a flash-flood watch through this afternoon for all Hawaiian islands.

The muggy weather is expected to hang around even longer, as forecasters do not see trade winds returning until the weekend.

Some areas of Central and Windward O'ahu were hit with extremely heavy rainfall, including the 6.04 inches that fell in the Poamoho area of Wahiawa during the 24-hour period that ended at 5 p.m. yesterday.

Part of the roof of the Kane'ohe post office collapsed during a period of heavy rain.

The rain and sticky conditions were attributed to "upper level short wave troughs" passing just north of the state, the weather service said. In addition, a frontal boundary approaching from the northwest is helping to keep trade winds away until the weekend.

Other areas of heavy rainfall yesterday included Wilson Tunnel (4.77 inches), Waikane (3.81), Waimanalo (2.87) and several spots on Kaua'i, notably Wailua (4.68).