A beekeeper using a smoker pot to calm his hives accidentally started a grass fire south of Sebastopol that charred about 2 acres Tuesday afternoon and burned an old barn to the ground.

The blaze was one of three fires in Sonoma County and the North Bay that crews battled on Tuesday as they were hampered by triple-digit temperatures and windy conditions that made containment more difficult. Smoke from the largest blaze, the Wragg fire, burning in Napa and Solano counties, drifted in heavy plumes over Sonoma County by Tuesday evening.

The weather will not help matters Wednesday as Santa Rosa is expected to see a high of 96 degrees, 12 degrees higher than the normal for late July, said Duane Dykema, a meteorologist with the National Weather Service. Cooler weather is set to return by Saturday, with highs in the mid-80s.

In the Sebastopol-area blaze, off Hessel Road, firefighters knocked down flames within a half hour, preventing its spread to a neighboring home. A chicken barn was completely destroyed.

Nine engine companies and 45 personnel responded to the fire, underscoring the extreme fire danger brought on by the heat and wind.

Firefighters suffered a setback on their efforts to extinguish the Wragg fire Tuesday afternoon as it jumped its primary containment line on its south side and spread over 400 acres in Solano County, forcing the evacuation of 200 residents near Vacaville.

Anxious residents looked on as smoke from the rekindled fire billowed across the eastern horizon. At least one resident spotted smoke drifting over the Imola bridge in Napa toward Sonoma and Petaluma. The fire, located southeast of Lake Berryessa, had been listed as 80 percent contained on Tuesday morning.

“Everything is dry out there and all it takes is one spark,” said Cal Fire spokeswoman Suzie Blankenship

Eleven air tankers and eight helicopters were dropping retardant and water on the blaze, which grew to 6,991 acres as of 8 p.m., when officials reported that the fire’s forward progress had been halted.

The fire has destroyed two outbuildings and damaged four others and one residence. A walnut orchard also was damaged and two vehicles destroyed, Cal Fire said.

The cause of the fire remains under investigation, but is believed to have started last Wednesday when a woman driving a burning vehicle pulled over on Highway 128 near Wragg Canyon Road in Napa County. The flames quickly spread to nearby brush alongside the road.

In Clearlake Tuesday, firefighters battled about a 10-acre fire that damaged three structures at the 16000 block of Dam Road. The fire forced the evacuations of the Cache Creek apartments and nearby residents, though they were expected to be able to return by 10 p.m.

Cal Fire reported that the fire was 90 percent contained by 7 p.m.

You can reach Staff Writer Bill Swindell at 521-5223 or bill.swindell@pressdemocrat.com. On Twitter @BillSwindell. You can reach Staff Writer Kevin McCallum at 521-5207 or kevin.mccallum@pressdemocrat.com. On Twitter @srcitybeat.