The lions have made at least three appearances on Kingridge Drive, a residential neighborhood in the southwestern part of the city, according to police.
Police posted video of the mountain lions Monday on Twitter, offering some tips.
VIDEO: Mountain lion runs past shocked onlookers outside SoCal brewery
Video shows mountain lion running past onlookers at SoCal brewery
They said people should be aware of their surroundings, watch out for pets and children, avoid feeding deer and refrain from approaching the big cats if spotted in any area.
The City of San Mateo also tweeted an alert, saying as the weather gets warmer, "we'll see more of our local wildlife taking chances closer to humans."