While direct hurricane landfalls are exceptionally uncommon, California has experienced tropical cyclones. Unique geographical and atmospheric conditions typically weaken these systems before they reach the coast. Despite the rarity of direct hits, tropical storm remnants can still bring substantial impacts, primarily heavy rainfall and associated hazards.
The Unfavorable Conditions for Hurricanes
The Pacific Ocean off California presents challenges for hurricanes. The cold California Current keeps sea surface temperatures lower than the 80°F (27°C) minimum required to sustain hurricane strength. As tropical cyclones move northward, they lose their primary energy source, weakening considerably.
Atmospheric conditions also steer and weaken these storms. The North Pacific High often creates winds that push tropical cyclones westward, away from the coast. Additionally, the eastern Pacific experiences increased vertical wind shear, which disrupts a hurricane’s organized structure, inhibiting its development or intensity. These factors create a natural barrier, making direct hurricane landfalls in California rare.
Past Encounters with Tropical Cyclones
California has a limited history of direct tropical cyclone impacts. The 1939 Long Beach Tropical Storm, also known as El Cordonazo, was the only tropical storm of record to make landfall in California in the 20th century. It struck near Long Beach on September 25, 1939, with sustained winds of around 50 mph, causing significant rainfall (Los Angeles 5.66 inches, Mount Wilson 11.60 inches), substantial flooding, and fatalities.
More recently, Hurricane Hilary in August 2023 tracked towards Southern California. Though Hilary weakened to a tropical storm and then a post-tropical cyclone before reaching California, its remnants brought historic rainfall and strong winds. Other notable instances include the remnants of Tropical Storm Nora (1997) and Hurricane Kay (2022), which also brought heavy rainfall and strong winds. While a hurricane in 1858 produced hurricane-force winds near San Diego, it did not officially make landfall.
A tropical depression has winds up to 38 mph, a tropical storm has winds from 39 to 73 mph, and a hurricane features sustained winds of 74 mph or more. Most tropical systems affecting California arrive as weakened tropical depressions or post-tropical remnants.
Understanding the Impacts
While direct hurricane landfalls are rare, tropical cyclone remnants can still cause significant disruption in California. The most prevalent impact is widespread heavy rainfall, leading to flash flooding, urban flooding, and dangerous mudslides. This risk is elevated in areas recently affected by wildfires, where burn scars can lead to rapid runoff and debris flows.
Though hurricane-force winds are uncommon, tropical storm-force winds or strong gusts can occur, capable of downing trees and causing localized power outages. For instance, Hilary produced gusts up to 87 mph in some mountainous areas. Coastal areas may experience increased surf, dangerous rip currents, and minor coastal erosion. These impacts differ from the extensive wind damage and storm surge typical of direct hurricane strikes.