A heat advisory for the area is in effect until 9 p.m. Saturday. Temperatures in Calistoga are expected to reach a low of around 59 degrees Friday night and a high of near 91 degrees on Saturday, with 5 to 7 mph winds. The chances of dry lightning are low but "not zero," the weather service said in its forecast discussion.

Firefighters in California's Napa County on Friday continued to battle the Pickett Fire, which burned more than 2,100 acres near the town of Calistoga.

The wildfire spread to more than 2,100 acres hours after erupting near Calistoga, authorities said. Evacuation orders were issued in parts of Napa County.