Over a three-hour period, some rain gauges have registered up to nearly two inches of rain from the weather pattern that has cloaked parts of the state.

The National Weather Service has issued a flash-flood watch for Oahu, Niihau and Kauai through midnight tonight.

A front approaching from the west combined with an upper-level trough is expected to make the atmosphere unstable near Kauai and Oahu, the weather service said. These conditions, combined with "abundant" low-level moisture, will increase the likelihood of heavy rainfall and flash flooding over the western end of the Hawaiian chain.

A flash-flood watch means that flash flooding is possible but not imminent in the watch area. Residents are advised to monitor weather forecasts and be prepared to act should a flash-flood warning be issued.

Off-and-on showers have brought moderate rainfall to most of Kauai and Oahu, but the southwest coast and Waimea Canyon on Kauai received the most rain with one gauge registering nearly two inches in a three-hour period, according to the weather service.

The good news is that tomorrow there should be increasingly sunnier skies, said Vladimir Ryshko, a National Weather Service meteorologist.

"I understand there's not been any serious flooding to this point," Ryshko said. "We're not expecting widespread flooding at this point.

"It's late in the season for this type of weather pattern."

On Oahu, the Palehua gauge on the southern end of the Waianae mountains recorded 1.59 inches of rain throughout the day while the Schofield South gauge registered 1.68 inches of rain.

Drivers should expect low visibility and ponding on roadways.