Smog Levels, Fire Risk Rise With the Heat : Weather: Residents hit beaches and pools, or just seek out shade, to escape sizzling temperatures, which are forecast to continue through Sunday.

Air pollution advisories were issued from Simi Valley to Santa Paula on Friday as sweltering temperatures and a lack of ocean breezes drove air pollution to unhealthful levels.

Smog levels were expected to remain high today in Simi Valley, Moorpark, Fillmore, Piru and Santa Paula, as a muggy heat wave hovers over coastal Southern California through the weekend.

Fire officials, meanwhile, cautioned that the sizzling temperatures and dry brush could make for an explosive mix in the Ventura County backcountry.

Such was the case on Friday when a small grass fire on Pine Mountain rekindled after being extinguished a week ago with 10,000 gallons of water. The ridge-top flare-up, already surrounded by fire lines, was doused within an hour.

“It’s extremely rare that we have a rekindle like that,” said Mike Preasmeyer, with the U. S. Forest Service’s Ojai Ranger District.

“That tells you how dry conditions are, especially in the pine litter.”

Preasmeyer added that forest rangers plan to step up patrols this weekend because today marks the opening of deer hunting season for much of the Ojai backcountry. Rangers will give verbal warnings to hunters for hazards such as illegal campfires.

“Even particles from an exhaust on a poorly maintained vehicle could cause a fire,” Preasmeyer said.

Forecasters from the National Weather Service said the unusually warm weather stems from a high-pressure system hovering over Arizona and is expected to last through Sunday.

“When you get a pattern like that, it will usually prohibit a sea breeze from coming in,” said forecaster David Gomberg. “And that’s what we count on every day to keep us cool.”

The same high-pressure system on Friday unleashed powerful thunderstorms over the San Jacinto Mountains and prompted officials to issue a flash flood watch for Palm Springs. Ventura County, however, is not expected to see rain in the next few days.

Temperatures on Friday topped 100 in Simi Valley, Thousand Oaks, Fillmore and Ojai. In Oxnard and Ventura, highs ranged from the high 70s to the mid-80s.

“I think everyone’s staying inside and sipping iced tea,” said Ventura County Fire Capt. R. Bosman, who works at the Tapo Canyon station, where the temperature peaked at 105 degrees at 2:45 p.m.

“I’ve been here for 10 years,” he said. “I don’t recall it ever being hotter than 105.”

Dispatchers with the county Fire Department reported no heat-related rescue calls. And officials with hospitals in Thousand Oaks and Santa Paula said they had treated no patients suffering heat exhaustion.

Still, residents in most of eastern Ventura County, particularly those with respiratory problems, were warned Friday to avoid strenuous exercise because of high smog levels.

In Simi Valley, the Pollutant Standard Index was 136 on a scale that considers anything above 100 unhealthy.

Gary Arcemore, a meteorologist with the Ventura County Air Pollution Control District, said possible effects of exercising on a smoggy day include difficulty breathing, burning eyes, headache and a runny nose.

Earlier Friday, residents were less concerned about health risks and more interested in finding some shade.

Mike Hart climbed down from the metal roof of the Thousand Oaks Library around 3 p.m. after working under the scorching sun for eight hours.

“It was so hot up there if you touched the metal for too long you would burn your hands,” he said.

“There’s pretty much nothing we can do but sweat a lot and hope for a breeze,” said Hart, who is supervising roof repairs that began two weeks ago.

“We just have to grin and bear it.”

The heat brought out kindness in some, such as the resident who greeted mail carrier Linda Morelock with a glass of iced tea midway through her postal route.

“That was really nice because we don’t have air conditioning in these trucks,” Morelock said.

Although beaches in Ventura were slightly more crowded than usual by the afternoon, Thousand Oaks’ city parks and streets were nearly deserted.

“I think everyone except me is inside in their air-conditioned homes,” said Thousand Oaks resident Cheryl DeWick, who was forced outdoors for three hours while exterminators fumigated her home.

“This is awful,” she said, trying to find shade under a small tree at Conejo Creek Park. “There’s no escaping it.”

Times staff writer Mack Reed and correspondent Matthew Mosk contributed to this article.