Santa Barbara County Early on the morning of January 9, mudflows struck
Montecito, which had been affected by the
Thomas Fire, and other areas of
Santa Barbara County. An estimated of rain fell within a five-minute period at approximately 3:30 a.m., causing mud and boulders from the
Santa Ynez Mountains to flow down creeks and valleys into Montecito. The debris flows were up to in height of mud, boulders and tree branches, moving at estimated speeds of up to into the lower areas of Montecito. Over 20,000 people lost power, and a section of
U.S. Route 101 (US 101) from Santa Barbara to
Ventura was shut down as sections filled with of mud and debris, some of which also reached beaches 2.25 miles (3.6 km) from the mountains. Following the closure, access to Santa Barbara from the Los Angeles area was limited to a detour around the
Los Padres National Forest or through the use of private ferries to Ventura. On January 11,
Amtrak train service was restored to Santa Barbara and US 101 was partially reopened as far west as
Carpinteria. The highway was fully reopened on January 21, after
Caltrans crews cleared of mud from the roadway. Approximately 21,000 residents of Santa Barbara and Ventura counties in high elevation zones affected by the Thomas Fire were evacuated, but low-lying areas were outside of the mandatory evacuation area. Warning messages sent by the
National Weather Service and the county government arrived too late to prompt Montecito residents to seek safe areas. Many residents in the mandatory evacuation zone, and most residents in the voluntary evacuation area, ignored warnings and stayed in their homes, probably a result of "evacuation fatigue" left over from the recent wildfires. The mandatory evacuation zone was expanded to cover a majority of Montecito's estimated 10,000 residents two days later (January 11) due to disruptions in electricity, gas, water, sewage and Internet, and due to emergency road works and ongoing search and rescue operations. The mudflows caused 23 confirmed deaths, mostly in the Montecito area. One body, that of two-year-old Lydia Sutthithepa, was never recovered. Over 150 people were hospitalized with various injuries, including four in critical condition. Writer
T.C. Boyle, whose home was proximate to both the fire and mudslides, documented the collective trauma in
The New Yorker magazine. Cleanup efforts began a week after the initial mudflows, with debris being sent to the
Ventura County Fairgrounds for sorting and the Calabasas Landfill for disposal.
Los Angeles County Parts of
Burbank and
Sun Valley, previously affected by the
La Tuna Fire in 2017, received of rain and were evacuated ahead of potential mudslides. A debris flow into a residential area of Sun Valley damaged 40 to 45 homes and carried a vehicle that struck a
natural gas pipeline, which began to leak. Mandatory evacuations were ordered for nearby areas of the
San Fernando Valley affected by the
Creek Fire before the storm, but no major damage was reported.
Orange and Riverside counties Heavy rain in
Corona, affected by the
Canyon Fire, covered streets with mud and flooded into several homes, but no major damage was reported. ==Response==