Climate of San Diego, California
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The Climate of San Diego, California is predominantly a semi-arid Mediterranean climate (Köppen climate classification BSh or Csa/Csb). It enjoys mild, sunny weather throughout the year.
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[edit] Average monthly temperatures
Average monthly temperatures range from about 57 Fahrenheit (14 °C) in January to 72 Fahrenheit (22 °C) in July, although late summer and early autumn are typically the hottest times of the year. Snow and ice are rare in the wintertime, typically occurring only inland from the coast when present. "May gray and June gloom", a local saying, refers to the way in which San Diego sometimes has trouble shaking off the fog that comes in during those months. Temperatures soar to very high readings only on rare occasions, chiefly when easterly winds bring hot, dry air from the inland deserts (these winds are called "Santa Anas").
[edit] Precipitation
San Diego has has on average 146 sunny days and 117 partly cloudy days a year. The average annual precipitation is less than 12 inches (300 mm), resulting in a borderline arid climate. Rainfall is strongly concentrated in the cooler half of the year, particularly the months December through March, although precipitation is lower than any other part of the U.S. west coast. The summer months are virtually rainless. Rainfall is highly variable from year to year and from month to month, and San Diego is subject to both droughts and floods. Thunderstorms and hurricanes are very rare.
[edit] Snow
Snow has been recorded falling on San Diego communities only five times in over 125 years of record-keeping[1]. Snow flurries were last seen in San Diego on December 24th, 1987, and the last measurable snowfall to hit various neighborhoods and suburbs around the city fell on December 13th, 1967.
[edit] Variation
Climate in the San Diego area 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 cool and damp within a few miles of the coast, but will yield to bright cloudless sunshine between about 5 and 15 miles inland -- the cities of El Cajon and Santee for example, rarely experience the cloud cover. This phenomenon is known as microclimate.
[edit] Compared to National Averages
On average San Diego sees 41 days with some precipitation while the rest of the country sees about 110. The national average for mostly sunny days is 213 while San Diego's is 267. San Diego's annual snowfall is 0 inches per year while the nation usually sees an average of 24.2 inches per year. The United States average for days above 90 degrees is 37.9 days while San Diego's is only 3 days[citation needed], and there are, on average 0 days below 32 degrees in San Diego, while the national average is 88 days. The average low temperature in January for the country is 26.5 degrees, and for San Diego it is 50 degrees. The Average high temperature in July for San Diego is 76 degrees, but the national average is 86.8 degrees.
[edit] Monthly Averages
| Weather averages for San Diego | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average high °F | 65.8 | 66.6 | 66.4 | 68.4 | 69.1 | 71.6 | 76.3 | 77.7 | 77.2 | 74.7 | 70.0 | 66.0 | 70.2 |
| Average low °F | 48.9 | 50.7 | 52.9 | 55.6 | 59.2 | 61.9 | 65.7 | 67.3 | 65.7 | 61.0 | 54.0 | 48.7 | 55.0 |
| Precipitation inches | 2.28 | 2.04 | 2.26 | 0.75 | 0.20 | 0.09 | 0.03 | 0.09 | 0.21 | 0.44 | 1.07 | 1.31 | 10.77 |
| Average high °C | 18.8 | 19.2 | 19.1 | 20.2 | 20.6 | 22.0 | 24.6 | 25.4 | 25.1 | 23.7 | 21.1 | 18.9 | 21.2 |
| Average low °C | 9.4 | 10.4 | 11.6 | 13.1 | 15.1 | 16.6 | 18.7 | 19.6 | 18.7 | 16.1 | 12.2 | 09.3 | 12.8 |
| Precipitation mm | 57.9 | 51.8 | 57.4 | 19.0 | 05.1 | 02.3 | 00.8 | 02.3 | 05.3 | 11.2 | 27.2 | 33.2 | 273.6 |
| Source: Weather.com [2] January 2006 | |||||||||||||
[edit] Santa Anas
The months of September through November bring winds that locals like to call, "Santa Anas". These winds, although only occurring about 10 days out of the year bring sometimes hot, but always dry conditions. Inland, and in mountain passes and canyons, they can burst out in gusts of 100 mph and can lower relative humidity to single digits, although by the coast they rarely see gusts of over 40 mph. They spread wildfires.
[edit] May and June clouds
During the months of May and June, a common natural occurrence brings a thin layer of clouds that covers coastal and inland communities. Some call it "May Gray", or "June Gloom", but these conditions usually burn off to completely sunny skies by noon.
[edit] See also
[edit] References
- ^ "Rowe, P.: "The Day it Snowed on San Diego" San Diego Union-Tribune, December 13, 2007.
- ^ Weather.com.
[edit] External links
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