Firefighters battled a brushfire on and off for more than 15 hours in Makua Valley yesterday as hot, dry conditions stymied crews trying to douse the blaze.

The fire scorched more than 100 acres in Makua Valley before more than two dozen firefighters contained the fire to an area about 50 feet in diameter at 4 p.m. yesterday, according to fire officials.

Still, firefighters, working in crews as large as two dozen, fought the fire well into the evening as flare ups occurred as late as 7:20 p.m.

The fire, which started about 2:30 a.m. yesterday and spread northwest toward the Yokohama Bay area on O'ahu's Leeward coast, posed no threat to property, said Fire Department Capt. Terry Seelig.

No injuries were reported.

"The fire has been contained, but there are hot spots in the area," said fire Capt. Earle Kealoha.

At least two dozen firefighters and two helicopters were at the scene yesterday. In addition to dousing the flames with water drops, helicopters were used to haul firefighting gear up steep terrain.

At least five companies responded to the scene, which is about 100 yards above Farrington Highway. Police were on scene as late as 7:30 p.m. last night providing traffic control.

The cause of the brushfire was under investigation.

A dramatic reduction in rainfall has increased the risk of brushfires as the leeward side of the Island experiences the hottest and driest months of the year.

Rainfall is down 60 percent from last year. Heavy rainfall in 2005 and 2006 prompted a lot of growth that has since died and turned into potential fuel, especially in leeward areas.

The dry conditions in Leeward O'ahu are not expected to improve anytime soon, according to the National Weather Service.

"This is trade wind weather, and most of the clouds and showers are affecting the windward side," said Jeff D. Powell, forecaster with the National Weather Service's Honolulu office. "The radar doesn't show a lot of showers in that area. It is pretty dry."

Since 2005, brushfires have scorched more than 6,000 acres of wild land on the leeward coast, according to the state Department of Land and Natural Resources.

Reach Peter Boylan at pboylan@honoluluadvertiser.com.