Due to flash flood warnings, Waymo has once again suspended its self-driving taxi service in San Francisco.

According to a user notification in Waymo's self-driving rideshare app, the company has temporarily suspended its autonomous taxi service in the San Francisco Bay Area on Thursday due to expected heavy rain. The notification stated, "Due to a flash flood warning issued by the National Weather Service, service is temporarily suspended." Earlier this week, Waymo announced upgrades to its fleet to enhance the operational stability of its self-driving taxis during power outages. On December 20, San Francisco experienced a power outage affecting tens of thousands of people, with some Waymo self-driving vehicles getting stranded in the middle of the road, causing or worsening traffic congestion. The company had suspended services at that time as well.