Tornadoes rarely occur in California because of the state's dry climate and low thunderstorm rate. According to the Tornado Project, California experienced approximately 300 tornadoes between 1950 and 2014. Californian tornadoes are generally small, weak and occur in California's Central Valley.
According to TheWeatherPrediction.com, tornadoes spawn from thunderstorms. Thunderstorms form when warm, moist air that collides with a cooler, drier air mass. This happens frequently in the flat plains region of the central United States nicknamed "Tornado Alley." This region receives large amounts of warm, moist air from the Gulf of Mexico. The shear forces become stronger with a greater difference in temperature and humidity. The moist air California receives from the Pacific Ocean is much colder. Consequently, California experiences fewer thunderstorms, and therefore fewer tornadoes, compared to states such as Texas, Oklahoma and Kansas.
Tornadoes occasionally spawn in other parts of the United States. Like California, the states in the Great Lakes region are generally too dry and too cold to support tornado formation for most of the year. Southeastern states, such as Florida, are extremely humid and famous for frequent, heavy thunderstorms. Despite its heat and humidity, the area rarely experiences tornadoes because cold fronts rarely penetrate it.