As you may have known, floods are approaching the coasts of California.
A strong Pacific storm is bringing soaking rain to Southern California, increasing the risk of flooding, mudslides, and debris floods. A multi-day rainfall would be starting on Thursday, 11/20/2025.
A storm drenched the region on Friday, causing the deaths of at least two people. A 71-year-old man died after his car got pushed off a flooding bridge in the Sacramento Valley. In addition to that, a father died trying to save his 5-year-old daughter from 20-foot waves at a state park along the central coast.
The flood threat has intensified as an atmospheric river, dropping moisture from the ocean, into the storm. Much of the Los Angeles area is under a risk of level 3 out of 4 of flooding rainfall on Saturday, 11/15/2025, according to the Weather Prediction Center.
An atmospheric river is typically 250 to 375 miles wide, and can stretch more than 1,000 miles, according to the National Oceanic and Atmospheric Administration. They may also bring flash floods, mudslides, landslides, and even sometimes destroying property and killing people. When atmospheric rivers pass over land, they tend to feel like hurricanes. Atmospheric rivers can happen all over the world. In fact, ten or more atmospheric rivers may be happening at once over the globe. But don’t worry, they tend to happen more frequently on the East coast than on the West. As the world starts to warm, atmospheric rivers will and can hold more moisture, which will lead to rainier atmospheric river events. An atmospheric river is pretty much defined as a region of water vapor. Also, according to NASA, atmospheric rivers would be significantly wider and larger than the ones we observe today, leading to more frequent occurrences of atmospheric rivers events, maybe even double the frequency. Although atmospheric rivers cause damage and may even cause death, atmospheric rivers are an incredibly important source of rainfall.
Areas recently burned by forest fires may experience debris flows or mudslides. Wildfires destroy the vegetation that would usually soak up all the water, but their heat can also alter the soil, which is creating a water-repellant layer just beneath the surface.
