Temperatures of 130 ☏ (54 ☌) or higher have been recorded as recently as 2005. The highest reliably recorded temperature in the world, 134 ☏ (56.7 ☌), was recorded in Death Valley on July 10, 1913. It is common in the summer for temperatures in the valley to surpass 120 ☏ (49 ☌).

In the northern portion of the Mojave Desert on the east side of the state is Death Valley, which has recorded temperatures among the highest in the world. The southeastern regions have a hot arid climate (Koppen BWh), similar to that of the Sahara Desert. The extreme southwest, around San Diego, has a subtropical semi-arid or steppe climate (Koppen BSh) as winters are drier there.

Palm Springs, a city in the Coachella Valley, averages high/low/mean temperatures of 75 ☏/50 ☏/63 ☏, (24 ☌/10 ☌/17 ☌) respectively during the period of cooler weather from November to April. East Los Angeles, the Gateway Cities, and parts of the San Gabriel Valley average the warmest winter high temps (72 ☏, 22 ☌) in all of the western U.S., and Santa Monica averages the warmest winter lows (52 ☏, 11 ☌) in all of the western U.S. ĭuring the cooler winter months (October–March), the Coachella Valley regularly has the warmest winter temperatures out of any place west of the Rocky Mountains. At the coast in Santa Monica, the average high in August is 75 ☏ (24 ☌), while in Burbank, approximately 10 miles (16 km) inland, the average high in August is 95 ☏ (35 ☌): a temperature gain of about two degrees Fahrenheit per mile. In Southern California, the temperature differences are approximately 4 ☏ in winter and 23 ☏ (2 ☌ and 13 ☌) in summer. For example, the average daily high in San Francisco in July and August is between 62 and 68 ☏ (17 and 20 ☌), and in Walnut Creek, some 20 miles (32 km) inland, the average daily high in July and August is 84 ☏ (29 ☌): a temperature gain of more than one degree (Fahrenheit) per mile. The temperature gradient between immediate coast and low-lying inland valleys in the south is about 7 ☏ (4 ☌) in winter, the coast being warmer, and in summer roughly 20 ☏ (11 ☌), the interior being warmer. Low-lying inland valleys, especially the Central Valley, have a hot-summer Mediterranean climate (Köppen Csa), with subtropical temperatures but a well-defined summer dry season and a foggy, rainy season in winter. Further inland, the climate becomes more continental, with some areas turning semi-arid (Köppen BSk), with colder winters and markedly hotter summers.

The cool California Current offshore, enhanced by upwelling of cold sub-surface waters, often creates summer fog near the coast, creating a warm-summer Mediterranean climate ( Köppen climate classification Csb).

Temperature range Snow on the ground in San Bernardino, Shandin Hills visible in the background The influence of the ocean generally moderates temperature extremes, creating warmer winters and substantially cooler summers in coastal areas. California's coastal regions, the Sierra Nevada foothills, and much of the Central Valley have a Mediterranean climate, with warmer, drier weather in summer and cooler, wetter weather in winter. The climate of California varies widely from hot desert to alpine tundra, depending on latitude, elevation, and proximity to the Pacific Coast. Golden Gate Bridge in fog Snow in the mountains of Southern California Summer in the Sierra Nevada at Lake Tahoe High precipitation in 2005 caused an ephemeral lake in the Badwater Basin of Death Valley. state of California Köppen climate types of California, using 1991-2020 climate normals.

Monthly averages palm desert weather