Though California is known for the mild climate along its southern shores, the state can claim a number of distinct climate zones.
Mark Twain’s famous 19th-century quote—“The coldest winter I ever spent was a summer in San Francisco!”—still stands. If you’re visiting “the City” in July or August, don’t bother bringing shorts—the weather is generally foggy and cool, with temperatures in the 50s and 60s. These cool temperatures persist along the Bay Area coastline as well. But if you head south to Silicon Valley or to the East Bay, expect temperatures to get up to 20–30° warmer and to see sun instead of fog.
Up along the North Coast, the weather stays about the same year-round: chilly, windy, and foggy. Temperatures can get up into the sunny 80s on rare hot summer days, and winter storms can pound the area with rain. These weather patterns turn milder toward coastal Sonoma in the southern Wine Country. Napa’s scorching hot valley summers and mild-to-cool winters are perfect for the grapes growing everywhere—and the tourists who come to drink them.
Lake Tahoe, Mount Shasta, Mount Lassen, Yosemite, and the Eastern Sierras all experience harsh, snow-filled winters that can close roads and wreak havoc with travel plans, but present ideal conditions for a multitude of winter sports. The short, hot summers also draw tourists out in droves.
Sacramento and the Central Valley boast high heat in the summers—often over 100°F—and cool but usually clear winters. The surrounding Gold Country, however, often receives snow in winter and can make roads here impassible.
The Central Coast has somewhat warmer temperatures than the Bay Area beaches, but you can still expect average cool temperatures and plenty of fog in the summer, with chill winds and some rain in the winter. The inland Central Coast wine regions mimic the climate patterns of the Wine Country and are more mild.
From the Los Angeles Basin down to San Diego and up the coast to Santa Barbara, temperatures are mild all year long. Expect fog on the beaches during the summer, cool days in the wintertime, and hotter temperatures in the inland valleys and Disneyland. For the best summertime beach weather in the state, head for San Diego.
The central and eastern deserts in the southern end of the state experience typical desert climates. That means mild, comfortable winters perfect for hiking and outdoor sports, but with nighttime temperatures in the 30s and 40s. The deserts’ dangerously hot summers can easily reach 110–120°F.
© Liz Hamill Scott from Moon California, 2nd Edition