California's weather is so varied that it's impossible to generalize about the state.
San Francisco's temperate marine climate means relatively mild weather year-round. In summer, temperatures rarely top 70°F (21°C; pack sweaters, even in Aug), and the city's famous fog rolls in most mornings and evenings. In winter, the mercury seldom falls below freezing, and snow is almost unheard of. Because of the fog, summer rarely sees more than a few hot days in a row. Head a few miles inland, though, and it's likely to be clear and hot.
The Central Coast shares San Francisco's climate, although it gets warmer as you get farther south. Seasonal changes are less pronounced south of San Luis Obispo, where temperatures remain relatively stable year-round. The Northern Coast is rainier and foggier; winters tend to be mild but wet.
Summers are cool around Lake Tahoe and in the Shasta Cascades. The climate is ideal for hiking, camping, and other outdoor activities, making these regions popular with residents of the state's sweltering deserts and valleys. From late November to early April, skiers also flock to this area, for terrific snowfall.
Southern California -- including Los Angeles and San Diego -- is usually much warmer than the Bay Area, and it gets significantly more sun. Even in winter, daytime temperatures regularly reach into the 60s (15°-20°C) and warmer. Summers can be stifling inland, but Southern California's coastal communities are comfortable. The area's limited rainfall is generally seen between December and mid-April, but it's rarely intense enough to be more than a slight inconvenience. It's possible to sunbathe throughout the year, but only die-hard enthusiasts and wet-suited surfers venture into the ocean in winter. The water is warmest in summer and fall, but even then, the Pacific is too chilly for many.
The deserts, including Palm Springs and the desert national parks, are sizzling hot in summer; temperatures regularly top 100°F (38°C). Winter is the time to visit the desert resorts (and remember, it gets surprisingly cold at night in the desert).
Avoiding the Crowds
Given California's pleasant summer weather (with relatively low humidity), the time between Memorial Day and Labor Day is high tourist season virtually everywhere -- except for desert areas such as Palm Springs and Death Valley, where sizzling temperatures daunt all but the hardiest bargain hunters. Naturally, prices are highest at this time, and they can drop dramatically before and after that period. (Exceptions to this rule include the aforementioned deserts and winter ski resorts.) Insider tip: Many Californians think the best time to travel the state is autumn. From late September to early December, crowds drop off, shoulder-season rates kick in, and winter rains have yet to start looming.
Banks, government offices, post offices, and many stores, restaurants, and museums are closed on the following legal national holidays: January 1 (New Year's Day), the third Monday in January (Martin Luther King Day), the third Monday in February (Presidents' Day), the last Monday in May (Memorial Day), July 4 (Independence Day), the first Monday in September (Labor Day), the second Monday in October (Columbus Day), November 11 (Veterans Day/Armistice Day), the fourth Thursday in November (Thanksgiving Day), and December 25 (Christmas). The Tuesday after the first Monday in November is Election Day, a federal government holiday in presidential-election years (held every 4 years, and next in 2012).
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.