The first robbery was reported at a U.S. Bank at 136 Second Ave. at about 4:40 p.m., San Mateo police said.
A tall, white man wearing a baseball hat, glasses and a light-colored sweater entered the bank, demanded money, and then left on foot with an undisclosed amount of cash, police said.
A second robbery was reported at 5:15 p.m. at a Chase bank at 3590 S. El Camino Real.
Witnesses said a man matching the description of the suspect in the first robbery came into the bank, demanded money and fled with cash.
No one was injured in either robbery, and no weapons were seen.
In the both robberies, witnesses told police the robber asked about getting medical attention before leaving the scene.
San Mateo police began checking with nearby medical centers and quickly got a report that a man matching the suspect description had shown up at Immediate Care at 60 N. El Camino Real.
Officers went to the clinic at about 5:35 p.m. and detained the suspect, Paul Stoliker, a transient from Moss Beach. He has since been arrested.
Investigators are looking into the possibility that he could be connected with other recent bank robberies in the area.