The bear sluggishly ambled along streets and into gardens in Monrovia, which sits at the foot of the San Gabriel Mountains.
The Monrovia Police Department said officers were keeping watch and state Department of Fish and Wildlife personnel were called to the neighbourhood.
It was believed to be the same bear seen a day earlier in Monrovia, where it is not uncommon for animals to wander out of the sprawling forest above the city.
The city’s bear safety web page notes that bears emerge from winter dens and return to the foothills in search of food when the weather warms up.
That typically occurs in spring, but southern California’s winter has been very mild.
Temperatures climbed to 80F (26.6C) in the San Gabriel Valley on Thursday.
Monrovia’s most famous bear visitor was Samson the Hot Tub Bear, who took a liking to back garden swimming pools in the 1990s.
He was eventually sent to live in the Orange County Zoo.