Rain continued to fall yesterday, with Kaua'i, the Big Island and O'ahu getting most of it.

The National Weather Service calls for more rain until at least the weekend.

The Big Island closed schools yesterday because of an early-morning downpour and experienced sustained rain in Na'alehu and southeast Ka'u into Volcano and in Puna areas including Pahoa, said Troy Kindred, administrator for the Hawai'i Civil Defense. At one point, floods in Kawa Flats caused the closure of Highway 11 between Pahala and Na'alehu, according to Kindred. Ka'u High, Pahala Elementary and Na'alehu Elementary schools were closed.

No damage was reported, Kindred said.

O'ahu Civil Defense said no one had reported any problems from rain but the agency remains on standby due to predictions of heavy showers.

A series of upper-level, low-pressure systems that have been hitting the Islands since February have resulted in rainfall that is between two to six times the normal amounts, according to the weather service.

The total inches of rain across the hardest-hit areas in the last three weeks is equivalent to the normal rainfall in those areas for the first three months of the year, said Andy Nash, director of operations at the Honolulu National Weather Service.

"For most places on Kaua'i, it's three months of rain in three weeks," Nash said. "It's unusual to have such a prolonged wet period but it's not like it's never happened before."

For instance, from Feb. 18 to yesterday, Kaua'i's Hanalei River had 34.82 inches of rain. O'ahu's Wilson Tunnel had 39.12 inches. On the Big Island, Mountain View had 37.78 inches. The normal rainfall in March for Hanalei is 13.4 inches; for Wilson Tunnel, 11.5 inches; and for Mountain View, 19.6 inches.

That's the result of four high-level, low-pressure systems developing just to the northwest of the state, bringing unstable conditions and tapping into an abundant moisture supply to the south, Nash said.

The systems arrived Feb. 19-24, March 1-3 and March 8 through Friday, with the latest onslaught ongoing.

For most of the winter, the Islands were under the influence of a high-pressure area that made for little rain, Nash said.

Now a low-pressure condition is causing the problem.

"The circulation pattern switched in February ... and we ended up in an area where we're just getting storm after storm," he said.

The condition will persist at least until the weekend.

The weather service has issued a flash flood watch for all islands through tomorrow.

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.