Four teenaged boys say smoking cigarettes on a sagebrush hillside accidentally led to the 100 metre by 200 metre grassfire on Orcrest Drive Wednesday afternoon.

The blaze came on the heels of a warning by forestry and City fire officials that a pending heat wave will cause an increased danger of more blazes in and around the Kamloops.

The Westsyde fire, described as fast moving by neighbourhood witnesses, came within a few hundred metres of houses before Fire and Rescue doused it into control by around 3:30 p.m.

Within sight of the fire fight, RCMP interviewed four boys approximately 17 years old who admitted to being the cause.

RCMP Staff Sgt. Grant Learned said the youths won't face charges since the incident was deemed accidental.

The owner of the house closest to the fire said she was driving home at the time and at first, thought her house was the source of the smoke.

"I was a little bit worried," said Marcie Shatula.

Although she quickly got over the immediate concern, she fears she might not be so lucky next time.

"I'm worried about the future potential of my house burning down now."

Shatula wasn't surprised by the teenagers' involvement, saying her boyfriend expressed concern a few days before when he noticed teens going up the hill behind their house, where a crude wooden fort has been built.

"He wanted to check it out and see what the kids were up to up there," she said.

Fire and Rescue assistant fire chief Dennis Fayers said in contradiction to what many might believe, the recent wet weather does not minimize the grassfire danger.

"All the rain does is make the sagebrush nice and plump and it burns just as well."

The grassfire occurred the day after 12 milimetres of rain fell on the region and the ground and brush was still saturated. A week or so of 30 C weather with no precipitation all but assures the fire-danger rating will spike, said Fayers.

"It's going to put it right into the high category again," he said. "It doesn't take that long to dry the grass out."

Fayers's warning was echoed by an official with the B.C. Forest Service. Fire information office Kevin Skrepnek said the coming heat wave, which begins in earnest Thursday, will quickly dry out the region.

June saw twice the normal amount of rainfall for the month, with 74.4 millimetres of precipitation recorded. That rendered the fire danger almost non-existent as of Wednesday morning, he said.

But the risk will be high or extreme once the thermometer reaches 36 C by Monday, said Skrepnek.

"It takes a lot less time to dry out than it does to get them wet," he said.

The temperature is expected to top 30 C on Friday and stay dry and well above the seasonal norm of 27 C for at least 10 days.

"The weather we're seeing in the forecast is pretty spectacular," said Skrepnek.

Adding to the danger is the likelihood of the 30-30 crossover, when temperatures climb above 30 C and the humidity slips beneath 30 per cent. He said this makes for ideal fire conditions.

"Based on the forecast I'm seeing, we should be hitting that by the weekend," Skrepnek. "The threat is pretty much there."

But crews are ready for anything. All forest service personnel sent to aid other provinces are back in B.C., said Skrepnek. A couple of air tankers are fighting fires in Colorado, but they can be back in the country within 24 hours.

Fire and Rescue is also prepared, with three bush trucks capable for responding to any wildland blaze within City limits, said Fayers.

"We're always ready," he said.