The only tropical storm to make landfall in California in the twentieth century arrived on September 25, 1939. The storm with 72 mph winds killed dozens of people on land and at sea. It also caused wide spread damage to homes and mass flooding.
This system was rated as a tropical storm for most if its life and as it struck land. Unnamed and sometimes called the 1939 Long Beach Tropical Storm or The Lash of St. Francis, the tropical depression that formed on September 15, 1939 near Central America.
Maximum winds sustained by this event were between 64 and 72 mph, but most areas saw moderate winds between 39 and 54 mph; these gales were enough to capsize and sink many vessels off the coast, accounting for the entire official death toll. The state estimated $2 million in damages, and when adjusted for inflation, damages accrue to $31 million.
A recent rainstorm following a heat wave just days before in the region dropped nearly five inches of rain. Floods were reported through Coachella valley and downtown Los Angeles through Inglewood; flood waters were between 2 and 4 feet deep.
The storm dropped heavy rain, with 5.66 inches falling in Los Angeles (5.24 inches in 24 hours) and 11.60 inches recorded at Mount Wilson, both September records.
Over three hours, one thunderstorm dropped nearly 7 inches of rain on Indio. 9.65 inches fell on Raywood Flat, and 1.51 inches on Palm Springs. 4.83 inches fell on Pasadena, a September record at the time. At the Citrus Belt near Anaheim, at least 4.63 inches of rain fell.
The only other known tropical cyclone to directly affect California is the 1858 San Diego Hurricane, and only three other eastern Pacific tropical cyclones have caused gale-force winds in the continental United States.