A vegetation fire burning east of Livermore scorched over 2,500 acres and was 60 percent contained as of Friday morning, Cal Fire said.
The Incident Commander told fire officials they need to work the hardest while the humidity is high and temperatures are low. He said he does not expect the weather to cooperature Thursday afternoon.
"That fire is trying to slowly smolder and get outside those lines," Cal Fire's Mike Martin said. "It is not contained. It's just slowed down right now. The worst is this afternoon when get wind on this fire, it's going to be a challenge to hold it in the perimeter we have right now."
Tesla Road has been closed down to all traffic at the intersection of Greenville Road and Cross Road. The road is expected to stay closed until 6:00 p.m. on Thursday. Motorists can use alternate routes of either Interstate-580 or Altamont Pass Road.
Cal Fire officials say the Tesla Fire is moving towards Tracy and they are afraid that homes are in the fire's path.
Cal Fire spokeswoman Pam Temmermand said the fire has been growing steadily since it was first reported Wednesday afternoon.
"If the wind dies down, maybe things will slow down a bit," Temmermand said. "But I know they're getting gusts of 12 to 13 (mph), so we'll see."
Hundreds of firefighters are battling the flames from the ground. Air drops are expected to resume late Thursday morning.
No injuries have been reported, but Cal Fire officials said one structure has been destroyed so far.
Reports of the fire came in on Wednesday at 2:45 p.m. off Tesla Road near Corral Hollow Road between Tracy and Livermore, Cal Fire officials said.