Читать книгу Afoot & Afield: Orange County. A Comprehensive Hiking Guide онлайн

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The inland zone, consisting of the Santa Ana Mountains and foothills, experiences somewhat more extreme daily and seasonal temperatures because it is less influenced by onshore flows of marine air. The higher summits of the Santa Ana Mountains, for example, have average temperatures in the 50s to 20s in winter, and the 80s to 50s in summer. Precipitation averages about 30 inches annually in the higher Santa Anas, which is just enough to support natural pockets of coniferous and broadleaf trees, such as pines, oaks, and maples. Almost every year, some fraction of the precipitation arrives in the form of snow, which briefly blankets the mountain slopes down to an elevation of about 3,000 feet.

Despite its reputation for a gentle climate, Orange County is occasionally subject to hot, dry winds called “Santa Ana winds” (after Santa Ana Canyon, just north of the Santa Ana Mountains). These winds occur when an air mass moves southwest from a high-pressure area over the interior United States out toward Southern California. As the air flows downward toward the coast, it compresses and becomes warm and dry. Low passes in the mountains or river valleys that act as wind gaps (such as Santa Ana Canyon) funnel these desertlike winds toward the coast. During stronger Santa Anas, common in late summer and fall, Orange County basks under warm, blue skies swept clear of every trace of pollution (except possibly smoke from wildfires). Temperatures along the coast can then reach record-high levels; the city of Orange, for example, once recorded a temperature of 119 degrees during a Santa Ana.