THIS ARTICLE is republished from The Conversation under a Creative Commons license. Dry conditions in Southern California in early January 2025 set the stage for a series of wind-driven wildfires that killed thousands of homes and other buildings in the Los Angeles area. Ming Pan , a hydrologist at the University of California-San Diego’s Center for Western Weather and Water Extremes, tracks the state’s water supply. They put Southern California’s drought into perspective using charts and maps. How Dry Is Southern California Right Now? In early January, soil moisture in much of Southern California was below 2 percent of the historical record for that day in the region. That is very low. On January 8, 2025, soil moisture content, measured down to about 40 inches (100 cm), was in the lowest 2 percent on record for that day in the Los Angeles area. Illustration: NASAHydrologists in California have been watching the sky very closely since October, when California’s water year begins. The country receives very little rain from May to September, so the end of autumn and winter is important to fill the reservoir and to build a snowpack to provide water. . California depends on the Sierra snowpack for about a third of its fresh water supply. However, Southern California is starting out the 2024-25 water year quite dry. The area receives rain from atmospheric rivers in November, but not much. After that, most of the atmospheric rivers that hit the West Coast from October to January travel north to Washington, Oregon, and Northern California. When the air is warm and dry, transpiration and evaporation also draw water from plants and soil. That leaves dry vegetation that can provide fuel for flying embers to spread wildfires, as seen in the Los Angeles area in early January. 2020 average. Illustration: Western Weather Center and Water Extremes
This Map Shows How Dry Southern California Is Right Now
