The animal was spotted in an "extremely rural" area near 400 Old La Honda Road, OES district coordinator Jeff Norris said.
"It was just seen wandering through the area, apparently, which would be normal for this time of year," he said.
"Our patrol people went and took a look ... They can't establish whether there was or wasn't a mountain lion there," Norris said. "However, it is the season when they are roaming."
A separate sighting was reported in Woodside last Tuesday when a resident claimed to have seen a mountain lion in the driveway of 5 Vintage Court.
On the morning of Aug. 31, a resident reported seeing a mountain lion in the 200 block of West Floresta Way in an unincorporated area near Portola Valley.
Earlier that month, on Aug. 21, someone claimed to have seen two mountain lions entering Edgewood Park and Natural Preserve.
Norris said that while the mountain lion seen today was in no way aggressive, residents should keep an eye out.
"People should be appropriately cautious of their surroundings," he said.
Anyone who sees a mountain lion is asked to call the sheriff's office at (650) 363-4915.