San Diego's economy is largely composed of agriculture, biotechnology/biosciences, computer sciences, electronics manufacturing, defense-related manufacturing, financial and business services, ship-repair and construction, software development, telecommunications, and tourism. The presence of the University of California, San Diego (UCSD) with the affiliated UCSD Medical Center promotes research in biotechnology.

The city of San Diego itself has deep canyons separating its mesas, creating small pockets of natural parkland scattered throughout the city. The same canyons give parts of the city a highly segmented feel, creating literal gaps between otherwise proximal neighborhoods and contributing to a low-density, car-centered built environment. Downtown San Diego is located on San Diego Bay. Balboa Park lies on a mesa to the northeast. It is surrounded by several dense urban communities and abruptly ends in Hillcrest to the north. The Coronado and Point Loma peninsulas separate San Diego Bay from the ocean. Ocean Beach is on the west side of Point Loma. Mission Beach and Pacific Beach lie between the ocean and Mission Bay, a man-made aquatic park. La Jolla, an affluent community, lies north of Pacific Beach. 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.

Climate

San Diego has a temperate, Mediterranean (Csa) climate when classified using the Koppen climate classification system, which is characterized by hot, dry summers and cool, wet winters. San Diego enjoys mild, mostly dry and plenty of sunshine throughout the year with 264 sunshine days annually. Temperatures vary little throughout the year. Summer or dry period of May to October are mild to warm with average high temperatures of 70 - 78°F (21 - 26°C) and lows of 55 - 66°F (13 - 19°C), and temperatures only exceed 90°F (32°C) 4 days a year. Winter or rainy period of November to April are mild and somewhat rainy with high temperatures of 66 - 70°F (19 - 21°C) and lows of 50 - 56°F (10 - 13°C).

Climate in the San Diego area and the rest of California often varies dramatically over short geographical distances, 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 cold and damp within a few miles of the coast, but will yield to bright cloudless sunshine between about 5 and 15 miles (9 - 24 km) inland; the cities of El Cajon and Santee for example, rarely experience the cloud cover. This happens every year in May and June. This phenomenon is known as microclimate.

Rainfall averages about 10 inches (251 mm) of precipitation annually, which occurs mainly during the cooler months of December through April with few wet days per month during the rainy period, but it could be heavy once it rains.

Like most of southern California, the majority of San Diego's current area was originally occupied by chaparral, a plant community made up mostly of drought-resistant shrubs. The endangered Torrey Pine has the bulk of its population in San Diego in a stretch of protected chapparral along the coast. The steep and varied topography, and proximity to the ocean creates a number of different habitats within the city limits, including tidal marsh and canyons. The influence of humans has altered existing habitats and has also created habitats that did not exist prior to human development, by construction of buildings, the introduction of new species, and the use of water for lawns and gardens. A number of species of parrots, including the Red-masked Parakeet and Red-crowned Amazon have established feral populations in urban neighborhoods such as Ocean Beach.

San Diego's broad city limits encompass a number of large nature preserves, including Torrey Pines State Reserve, Border Field State Park, Mission Trails Regional Park. Torrey Pines State Preserve and a coastal strip continuing to the north is the only location where the rare species of Torrey Pine, P. torreyana torreyana, is found. Due to a combination of the steep topography that prevents or discourages building, and some efforts for preservation, there are also a large number of canyons within the city limits that are nature preserves, including Tecolote Canyon Natural Park, and Marian Bear Memorial Park in the San Clemente Canyon, as well as a number of small parks and preserves.

According to education rankings released by the U.S. Census Bureau, 40.4 percent of San Diegans ages 25 and older hold bachelor's degrees. The census ranks the city as the ninth most educated city in the United States based on these figures.

Public colleges and universities in the city include University of California, San Diego (UCSD), San Diego State University (SDSU), California State University San Marcos (CSUSM) and the San Diego Community College District, which includes San Diego City College, San Diego Mesa College, and San Diego Miramar College.

Private colleges and universities in the city include Alliant International University (AIU), Coleman University, Design Institute of San Diego (DISD), John Paul the Great Catholic University, National University, NewSchool of Architecture and Design, Pacific Oaks College, The Art Institute of California, San Diego, Point Loma Nazarene University (PLNU), San Diego Christian College, Southern States University (SSU), Woodbury University School of Architecture's satellite campus, and University of San Diego (USD).

There is one medical school in the city, the UCSD School of Medicine. There are three ABA accredited law schools in the city, which include California Western School of Law, Thomas Jefferson School of Law, and University of San Diego School of Law. There is also one unaccredited law school, Western Sierra Law School.

Many popular museums, such as the San Diego Museum of Art, the San Diego Natural History Museum, the San Diego Museum of Man, and the Museum of Photographic Arts are located in Balboa Park. The Museum of Contemporary Art San Diego (MCASD) is located in an ocean front building in La Jolla and has a branch located at the Santa Fe Depot downtown. The Columbia district downtown is home to historic ship exhibits as well as the San Diego Aircraft Carrier Museum featuring the USS Midway aircraft carrier.

San Diego has a growing art scene. "Kettner Nights" at the Art and Design District in Little Italy has art and design exhibitions throughout many retail design stores and galleries on selected Friday nights. "Ray at Night" at North Park host a variety of small scale art galleries on the second Saturday evening of each month. La Jolla and nearby Solana Beach also have a variety of art galleries.

The San Diego Symphony at Symphony Towers performs on a regular basis and is directed by Jahja Ling. The San Diego Opera at Civic Center Plaza was ranked by Opera America as one of the top 10 opera companies in the United States. Old Globe Theatre at Balboa Park produces about 15 plays and musicals annually. The La Jolla Playhouse at UCSD is directed by Christopher Ashley. The Joan B. Kroc Theatre at Kroc Center's Performing Arts Centeris is a 600-seat state-of-the-art theatre that hosts music, dance and theatre performances. The San Diego Repertory Theatre at the Lyceum Theatres in Horton Plaza produces a variety of plays and musicals. Serving the northeastern part of San Diego is the California Center for the Arts in Escondido, a 400-seat performing arts theater.

Tourism has affected the city's culture, as San Diego houses many tourist attractions, such as SeaWorld San Diego, Belmont amusement park, San Diego Zoo, San Diego Wild Animal Park, and nearby Legoland. San Diego's Spanish influence can be seen in the many historic sites across the city, such as the Spanish missions and Balboa Park. Cuisine in San Diego is diverse, and includes European-American, Mexican-American, and Asian-American cuisine. Annual events in San Diego include Comic-Con, San Diego/Del Mar Fair, and Street Scene Music Festival.