page_title: San Diego
section_title: Climate
hierarchical_section_title: San Diego / Geography / Climate
caption_attribution_description: English: Surfers at Pacific Beach, San Diego, California Español: Surfeadores en Pacific Beach, San Diego, California
context_page_description: San Diego is a city in the U.S. state of California on the coast of the Pacific Ocean, approximately 120 miles south of Los Angeles and immediately adjacent to the border with Mexico. With an estimated population of 1,423,851 as of July 1, 2019, San Diego is the eighth-largest city in the United States and second-largest in California. It is part of the San Diego–Tijuana conurbation, the second-largest transborder agglomeration between the U.S. and a bordering country after Detroit–Windsor, with a population of 4,922,723 people. The city is known for its mild year-round climate, natural deep-water harbor, extensive beaches, long association with the United States Navy, and recent emergence as a healthcare and biotechnology development center.
  San Diego has been called "the birthplace of California". Historically home to the Kumeyaay people, it was the first site visited by Europeans on what is now the West Coast of the United States. Upon landing in San Diego Bay in 1542, Juan Rodríguez Cabrillo claimed the area for Spain, forming the basis for the settlement of Alta California 200 years later.
context_section_description: San Diego has one of the top-ten best climates in the United States, according to the Farmers' Almanac and has one of the two best summer climates in the country as scored by The Weather Channel. Under the Köppen–Geiger climate classification system, the San Diego area has been variously categorized as having either a semi-arid climate (BSh in the original classification and BSkn in modified Köppen classification with the n denoting summer fog) or a Mediterranean climate (Csa). San Diego's climate is characterized by warm, dry summers and mild winters, with most of the annual precipitation falling between December and March. The city has a mild climate year-round, with an average of 201 days above 70 °F (21 °C) and low rainfall (9–13 inches [230–330 mm] annually).
  The climate in San Diego, like most of Southern California, often varies significantly over short geographical distances, resulting in microclimates. In San Diego, this is mostly because of 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 keeps the air cool and damp within a few miles of the coast, but yields to bright cloudless sunshine approximately 5–10 miles (8.0–16.1 km) inland. Sometimes the June gloom lasts into July, causing cloudy skies over most of San Diego for the entire day. Even in the absence of June gloom, inland areas 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 (10 °C) and August highs of 78 °F (26 °C). The city of El Cajon just 10 miles (16 km) inland from downtown San Diego, averages January lows of 42 °F (6 °C) and August highs of 88 °F (31 °C).
  A sign of global warming, the average surface temperature of the water at Scripps Pier in the California Current has increased by almost 3 degrees since 1950, according to scientists at Scripps Institution of Oceanography.
  Annual rainfall along the coast averages 10.65 inches (271 mm) and the median is 9.6 inches (240 mm). The months of December through March supply most of the rain, with February the only month averaging 2 inches (51 mm) or more. The months of May through September tend to be almost completely dry. Although 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 areas can receive 11–15 inches (280–380 mm) per year. Variability from year to year can be dramatic: in the wettest years of 1883/1884 and 1940/1941 more than 24 inches (610 mm) fell, whilst in the driest years there was as little as 3.2 inches (80 mm). The wettest month on record is December 1921 with 9.21 inches (234 mm).
  Snow in the city is so rare that it has been observed only six times in the century-and-a-half that records have been kept. In 1949 and 1967, snow stayed on the ground for a few hours in higher locations like Point Loma and La Jolla. The other three occasions, in 1882, 1946, and 1987, involved flurries but no accumulation. On February 21, 2019, snow fell and accumulated in residential areas of the city, but none fell in the downtown area.
caption: Surfers at Pacific Beach
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