California is taking a beating from an unusually destructive 2026 Pacific hurricane season

In 2026, California experienced an exceptionally active eastern Pacific hurricane season, which is unusual because the state is not typically associated with tropical weather. For only the second time in history, national forecasters issued a tropical storm watch for Southern California as Tropical Storm Rachel approached in October. A tropical storm watch is a warning that tropical storm conditions (sustained winds of 39 to 73 mph) are possible in the area within 48 hours. The first such watch was issued in 2023 for Hurricane Hilary. This season also saw three hurricanes affecting Hawaii, a rare event, and Hurricane Marie generating large waves that damaged oceanfront homes near Los Angeles. Rachel weakened before reaching California but still caused coastal flooding, damaged homes, and brought heavy rain to communities from San Diego to Las Vegas, where flooding occurred.

California’s history with tropical storms is limited but notable. The earliest recorded storm was the 1858 San Diego Hurricane, a Category 1 hurricane that struck San Diego County, causing significant damage despite the region’s small population at the time. The only known tropical storm to make landfall in California was in 1939, hitting Long Beach in Los Angeles County. It brought tropical-storm-force winds and over 4 inches of rain to some areas. The U.S. Weather Bureau, the predecessor to the National Weather Service, opened a Southern California office in 1940 in response to this storm. While a few other storms came close to California in the 1970s, they weakened or changed course. Recent storms like Hurricane Hilary in 2023 and Hurricane Nora in 1997 also affected the region, either by making landfall in Baja California or bringing tropical-storm-force winds to California.

El Niño is a natural climate pattern characterized by unusually warm water in the eastern tropical Pacific Ocean. It increases the frequency of storms in the eastern North Pacific, including hurricanes, because warmer sea surface temperatures provide the energy needed for these storms to form and strengthen. During El Niño years, the waters off Southern California and northern Baja California are usually too cool to support hurricanes. However, if a storm moves quickly or is supported by strong upper-level winds, it can survive these cooler temperatures and approach California. For example, Tropical Storm Rachel in 2026 was able to maintain its strength partly due to anomalously warm sea surface temperatures off Baja California. This highlights how El Niño can elevate the risk of tropical storms affecting California, even though such events remain rare.

The primary impact of tropical storms and hurricanes on California is rainfall, which can cause significant problems despite the state’s arid climate. Southern California typically receives little rainfall during summer and early fall, so even moderate amounts can lead to flash flooding. Tropical Storm Rachel dumped up to 6 inches of rain in parts of Southern California, including over 1 inch at San Diego International Airport in one weekend. This amount is double the typical October precipitation for San Diego. While these rainfall amounts are small compared to storms in regions like Florida, they can overwhelm dry riverbeds, streets, and urban drainage systems in the Southwest. The National Hurricane Center warned of flash flooding in California and other parts of the Southwest before Rachel’s landfall, emphasizing the risks posed by even weaker tropical systems in normally dry areas.