No structures were threatened and no injuries had been reported in the Trail Fire, which was spotted about 10 a.m. Wednesday. The cause of the fire had been determined to be a lightning strike, Davis said.
Also sparked by lightning was the Hell's Kitchen Fire, which had burned about 31 acres 8 miles north of Fayette, near Yuba Lake.
Fire Information Officer Jill Ivie said that blaze, with no containment time estimated, continued to burn Thursday on Bureau of Land Management holdings. The area is both remote and rugged with no structures at risk; firefighting resources were in the process of being gathered.
Full containment had been reached on both the Mount Olympus Fire in Salt Lake County and Cache County's Aspen Fire; neither of those lightning-caused blazes was thought to have burned more than an acre.
Another lightning blaze, the Sinbad Fire 30 miles east of Moab, remained at 438 acres as crews worked to complete containment, which reached 20 percent by Thursday evening.
In Weber County, investigators were looking into the cause of a 150-acre fire that broke out near the Weber Wildlife Federation, north of Pineview Reservoir. That blaze, dubbed the Avon II Fire, was 90 percent contained Thursday night, with a few hot spots near the edge that crews plan take care of Friday.
Although most current wildfires are small in size, Utah's parched conditions have prompted crews to be aggressive in their firefighting responses.
Once again on Thursday, most of the state was under "Yellow," or unhealthy breathability ratings as both smoke drifting into Utah from out-of-state fires and the smaller blazes within the state and high temperature-induced inversions degraded air quality.
Reporter Michael McFall contributed to this story.