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.

The blaze remains at 2,133 acres and is 0% contained, according to Division Chief Ryan Isham in a Cal Fire LNU morning briefing. A strong wind has pushed the fire eastward, sending it from the Pickett Lane area down in the floor of Napa Valley into the Aetna Springs side of Pope Valley.

As the Pickett Fire outside Calistoga grew to 2,133 acres, Napa County authorities ordered evacuation from a fourth Upvalley area as hundreds of firefighters battled the blaze.

The Pickett Fire near Calistoga in Napa County expanded to 3,993 acres Friday night as firefighting efforts continued with night-flying helicopters and containment held at 7%, Cal Fire said.