Chapter Two: Physical Features

San Diego is located just 17 miles north of Mexico and runs along the Pacific Ocean for 70 miles to the west. The Southern California city also boasts a mild climate year-round. The city’s geography is best known for its hillsides, canyons, and beach areas. It’s divided by canyons and hills that allow for parkland and entertaining areas. San Diego is divided from a northern and southern area by a river valley known as the San Diego River that runs through the middle.

Downtown San Diego is located on San Diego Bay. Balboa Park lies on a mesa to the northeast, surrounded by dense urban communities including Hillcrest to the north. The Coronado and Point Loma peninsulas separate San Diego Bay from the ocean. Ocean Beach is on the northwest side of Point Loma. Mission Beach and Pacific Beach lie between the ocean and Mission Bay, a man-made aquatic park. La Jolla lies north of Pacific Beach and west of Mira Mesa. The city contains more than 100 identified neighborhoods. [3]

The Cuyamaca Mountains and Laguna Mountains rise to the east of the city, and beyond the mountains are desert areas. Cleveland National Forest is a half-hour drive from downtown San Diego. Numerous farms are found in the valleys northeast and southeast of the city. San Diego County has one of the highest counts of animal and plant species that appear on the endangered species list among counties in the United States.[1]

The climate in the San Diego area, like much of California, often varies significantly over short geographical distances resulting in microclimates. In San Diego's case this is mainly due to the city's topography (the Bay, and the numerous hills, mountains, and canyons). Frequently, particularly during the "May gray/June gloom" period, a thick "marine layer" cloud cover will keep the air cool and damp within a few miles of the coast, but will yield to bright cloudless sunshine approximately 5–10 miles (8.0–16 km) inland. This happens every year in May and June. Even in the absence of June gloom, inland areas tend to experience much more significant temperature variations than coastal areas, where the ocean serves as a moderating influence. Thus, for example, downtown San Diego averages January lows of 50°F and August highs of 78°F. The city of El Cajon, just 10 miles northeast of downtown San Diego, averages January lows of 42°F and August highs of 88°F. However sometimes the June gloom can last for several days even into July causing cloudy skies for San Diego for the entire day. Rainfall along the coast averages about 10 inches (250 mm) of precipitation annually, which occurs mainly during the cooler months of December through April. Though there are few wet days per month during the rainy period, rainfall can be heavy when it does fall. Rainfall is usually greater in the higher elevations of San Diego; some of the higher elevation areas of San Diego can receive 11–15 inches (280–380 mm) of rain a year. [2]

[1] http://travel.nationalgeographic.com/travel/city-guides/san-diego-california/

[2] http://en.wikipedia.org/wiki/San_Diego#Geography

[3] http://www.answers.com/topic/san-diego-geography-and-climate