Meanwhile, Morgan County's Tunnel Hollow Fire quintupled in size overnight and had topped 1,200 acres as Tuesday drew to a close.
"With the wind and hot, dry weather we're expecting a lot more activity on this fire," Fire Information Officer Jason Curry said.
The Tunnel Hollow Fire, ignited by lightning on Sunday, was burning in Weber Canyon, 5 miles east of Morgan. It was 10 percent contained Tuesday night.
Curry said nearby Interstate 84 remained open, but motorists should be prepared for lots of smoke cutting their visibility, as well as increased fire engine traffic.
About 135 firefighters, aided by three water-bearing helicopters and a fire retardant-laden air tanker, were being thrown into the fray on Tuesday, Curry said.
Back in Tooele County, the lightning-caused Sheep Fire also was producing prodigious columns of smoke. It had scorched more than 1,800 acres in the area of Lookout Pass on the Pony Express Trail near Vernon. Crews late Tuesday were conducting a "backfire" operation, setting fire to unburned brush along the inside of the perimeter to remove fuel and keep the fire from spreading.
Conditions were not expected to improve soon, as the National Weather Service put roughly the western half of the state under a "Red Flag" wildfire risk advisory into late Tuesday evening.
Fire Information Office Teresa Rigby said the Sheep Fire was out of control, though it did seem to slow its growth early Tuesday afternoon.
The Lion Peak Fire, also lightening-sparked, also was out of control and expected to top several hundred acres if not more.
In Carbon County, a 100-acre fire was burning near Sunnyside. Fire officials said it was moving away from the town.