Santa Barbara County Climate
Santa Barbara County occupies more than 2,700 square miles, most of which is sparsely populated and mountainous. The county is situated among a series of transverse mountain ranges, the only ranges within the continental United States to trend in an east-westerly direction. Most of the county's developed areas are located along the coastal plain and in the inter-mountain valleys. Santa Barbara County's climate is typically warm and dry in summer and cool and wet in winter, close to that of a Mediterranean-type climate. Most of the county's rivers, creeks, and streams remain dry during the summer months. The proximity of the Pacific Ocean tends to moderate Santa Barbara's climate and temperatures near the coast, while adjacent steep mountain ranges paralleling the coast produce a significant "orographic effect." This occurs when storms approaching the county from the Pacific Ocean are forced upward against the mountains resulting in an increased precipitation release with the increased topographic elevation. This orographic effect, in conjunction with the steep, short watersheds, occasionally results in flash flooding along the county's south coast.
Precipitation within the county varies greatly from season to season and with each location. Average annual precipitation ranges from a minimum of about 8 inches in the Cuyama Valley to over 36 inches at the apex of the Santa Ynez Mountains. Snow is common at the county's highest elevations that are in excess of 6,600 feet above sea level. Climate studies have determined that drought periods occur regularly and may last as long as a decade or more. The most recent drought lasted from 1986 to 1991, during which water storage in the county's major reservoirs was nearly depleted. With a mean annual rainfall of 18.55 inches, only 6.41 inches of rain were recorded in downtown Santa Barbara in 2007 - the driest year of record.
Although rainfall within the County is moderate on average, some winters yield well over twice the average. The maximum annual rainfall of 46.97 inches was recorded in downtown Santa Barbara in 1998. In addition, Santa Barbara County is occasionally subject to short duration rainfall of very high intensity (see table below). Due to it's pronounced topography and variable rainfall, Santa Barbara County has been subject to numerous periods of flooding. Significant floods were reported by Spanish Missionaries as long ago as the late 18th Century. 20th Century flood years include 1914, 1941, 1948, 1969, 1978, 1983, 1992, 1995, and 1998.
El Nino Southern Oscillation (ENSO) refers to oceanic & atmospheric characteristics that tend to impact short-term climate variability. El Nino is the warming of ocean surface temperature in the Eastern Pacific, whereas La Nina is an ocean temperature cooling trend. The former is often associated with potentially greater than normal precipitation, while the latter tends to characterize slightly drier than normal conditions.
ENSO typically has a variable influence in Southern California (incl. Santa Barbara County). An El Nino (& La Nina) strength is typically categorized on a scale of Strong, Moderate, and Weak - a function of "Nino 3.4 Region" difference in sea-surface temperature readings.
Some of the wettest years on record are classified as strong El Nino's: 1983, and 1998 - yet other strong El Nino's have produced drier than normal years.
Many regional inconsistencies in "El Nino vs Observed Rainfall" exist (see graph below).
Average temperatures in Santa Barbara tend to be moderate as is illustrated by the graph below. However, extreme highs and lows may also occur. Temperatures as high as 109 degrees and as low as 20 degrees Fahrenheit have been recorded at the Santa Barbara Airport within the last 60 years.
|Temperature graph produced by the NWS.|
Pacific High Pressure System
Santa Barbara County's climate is primarily influenced by the Pacific High Pressure System. During the dry months high pressure usually dominates the area northeast of Hawaii. In winter, it weakens and moves to the south allowing cold storm systems to enter the area from the northwest. When the region of high pressure is situated further north than normal, a "blocking high" results. The storm track is kept further north than normal and California receives little or no precipitation. The "blocking high" is responsible for most of California's droughts.
For additional information on Santa Barbara's Climate visit the National Weather Service.