Bad news for asthma sufferers and anyone without air conditioning.

The weekend's voggy weather is likely to stick around through tomorrow, according to the National Weather Service.

The recent shift from trade winds to light southeasterly breezes produced these sticky conditions and brought the hazy air from the Big Island's Kilauea Volcano to Maui and O'ahu.

This kind of wind pattern is uncommon during the early summer months, said lead forecaster Roy Matsuda.

"This is normally something that occurs during the winter months, late fall and early spring," Matsuda said from the air-conditioned Honolulu office of the National Weather Service. "The summer months are the steadiest trade-wind days, when it blows maybe about 90 to 95 percent of the time."

Southeasterly winds are rare in Hawai'i, where trade winds dominate much of the wind pattern, Matsuda said. Wind from the south — commonly referred to as Kona wind — doesn't bring the vog with it, he said.

A high-pressure ridge is blocking the usual trade wind, causing the wind shift that resulted in yesterday's hazy, voggy conditions.

"It's been quite hazy, like we're in L.A.," said Willy Nagamine, manager of the state Department of Health's Clean Air Branch, which operates six air-quality monitoring stations on O'ahu. "(The vog) is mainly made up of fine particulates that don't disperse as well because of the light winds."

Today winds will remain light and from the southeast, 9 to 11 mph, according to the National Weather Service. That wind pattern will continue through the early part of tomorrow. By afternoon, trade winds are expected to return and remain through the rest of the week.

Humidity in Honolulu yesterday was about 65 percent, though it may have felt stickier to many residents, Matsuda said.

The state's air-quality monitoring stations did not report any cause for alarm. But those with respiratory ailments should take precautions, Nagamine said.

"Plan your day accordingly," he said.

Reach Catherine E. Toth at ctoth@honoluluadvertiser.com.