California Flooding: Which Areas Are at Risk

California faces a high risk of flooding due to a powerful atmospheric river. This phenomenon will impact the state during Christmas week 2025. Authorities such as the Weather Prediction Center (WPC) have issued level 3 out of 4 alerts for more than 17 million people. Especially in the south.

The new storm and another following it are prompting new evacuations in areas affected by fires in the Los Angeles area and an unusually high flooding risk, according to forecasters, with rainfall equivalent to several months and potentially deadly floods expected in southern California.

At least one person has died after flash floods from the first storm inundated Redding, about 240 kilometers north of Sacramento, according to Redding Mayor Mike Littau, who said police and firefighters conducted water rescues on Sunday.

Which areas are most vulnerable?

Therefore, Southern California leads the alerts, with metropolitan areas of Los Angeles, San Bernardino, and Santa Barbara under threat of flash floods. Additionally, the north is experiencing river rises such as the South Yuba in Placer and rescues in Humboldt and Shasta. In these areas, water reached critical levels over the weekend. In the long term, coastal cities such as San Francisco, Oakland, Long Beach, Huntington Beach, Newport Beach, Seal Beach, and San Diego could flood. This would occur with a 3-meter rise in sea level, according to NOAA.

Aggravating factors

Likewise, heavy rainfall of up to 10-20 cm on coasts and valleys combined with areas burned by previous fires increase the danger of landslides and debris flows. For example, the Sierra Nevada and Cascades expect heavy snow, but lower basins will suffer stream and river overflows. Recently, Shasta County remained on alert through December 22.

Recommended measures

Consequently, residents should monitor NWS alerts, avoid flooded roads, and prepare for evacuations. Local teams are reviewing 46,000 storm drains to mitigate damage. Thus, the storm could extend through Saturday, affecting holiday celebrations with possible power outages and water rescues.