As Dave Eskelsen explains the unusual number of power outages Monday through-out northern Utah, "It finally warmed up and became summer."

Eugene Van Cor, spokesman for the National Weather Service's regional office in Salt Lake City, said high temperatures Monday ranged from 107 in Arches National Park near Moab and 106 in St. George to the upper 80s in the northern valleys. Bountiful's high was 86 and Salt Lake City's was 88.On Tuesday the high for Salt Lake City was expected to reach 91 degrees. "That would be the first time we've hit 90 in June" this year, he said.

Although summer hit with a thud, this is the latest date on record that Salt Lake City has warmed up to 90 degrees.

The warming triggered an ozone pollution crisis in which state health officials called for a voluntary no-driving day, increased stress on fire-fighters in southern Utah and contributed to the spread of a blaze that is burning out of control.

"The heat is a problem for the firefighters, working under those conditions," Van Cor said. Also, extreme heat dries out the desert brush, making good tinder for wild-fires.

Monday's warmth prompted many northern Utahns to turn on their air conditioners. With the sudden added demand, isolated parts of the electrical power grid failed.

It wasn't that too little power was available, according to Esk-el-sen, but the increased usage knocked out worn switches, overloaded fuses and circuit breakers.

The hot weather created the perfect - or rather not-so-perfect - conditions for dangerous levels of ozone air pollution. High levels of ozone, visible as brown haze, prompted the Department of Environmental Quality to issue a health advisory Monday and to renew it Tues-day.

"It will likely be in effect (Wednesday), too," said DEQ spokeswoman Carol Sisco.

The air pollution problems along the Wasatch Front are regular summertime occurrences as sunlight and hot weather causes certain airborne chemicals, most of which come from auto emissions, to combine into the brown haze that shrouds the valley. It gets particularly bad as the summer days wear on, from about 3 p.m. to 5 p.m. on those hot days with little or no wind.

Even without the issuance of formal health advisories, Sisco said these conditions combine to make the air dangerous. Small children, the elderly and those with heart or breathing problems should not exert themselves outside, and those who exercise should do so early in the morning or late in the evening when ozone levels are lower.

"Better yet, go to a gymnasium," Sisco said.

The DEQ issued a request Tuesday for motorists to refrain from driving, gas up their cars only in the evening, and avoid using small engines, paints and solvents. The request was likely to be renewed for Wednesday.

In the rough Beaver Dam Mountains of extreme southern Utah and northern Arizona, the Bulldog fire continues to burn out of control but is 75 percent contained. The flames are eight to 10 miles southwest of St. George. Since Saturday, about 6,200 acres have been burned.

"Crews made good progress mopping up the fire in the Beaver Dam Wilderness on Monday," said Bette Arial, spokeswoman for the Color Country South Zone Interagency Fire in St. George.

"Some portions of the wilderness were allowed to burn out, due to crew safety concerns," she added.