California is the most populous state in the United States, and the third largest by land area, after Alaska and Texas; it is also the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil. California is located on the West Coast of the United States, bordered by Oregon to the north, Nevada to the northeast, Arizona to the southeast, the Mexican state of Baja California to the south, and the Pacific Ocean to the west. Its four largest cities are Los Angeles, San Diego, San Jose, and San Francisco. Much of the state has a Mediterranean climate, with cool, rainy winters and dry summers. The cool California Current offshore often creates summer fog near the coast. Further inland, one encounters colder winters and hotter summers. California's geography ranges from the Pacific coast to the Sierra Nevada mountain range in the east, to Mojave desert areas in the southeast and the Redwood–Douglas fir forests of the northwest. The center of the state is dominated by the Central Valley, one of the most productive agricultural areas in the world. California is the most geographically diverse state in the nation, and contains the highest (Mount Whitney) and lowest (Death Valley) points in the contiguous United States. Almost 40% of California is forested, a high amount for a relatively arid state.