page_title: Santa Cruz Mountains
section_title: Climate
hierarchical_section_title: Santa Cruz Mountains / Climate
caption_attribution_description: English: Red outlines mark the locations where the satellite detected active fire. A narrow but dense plume of smoke slices across the mouth of Monterey Bay, stretching past the city of Santa Cruz toward Monterey. The landscape of this part of California is one of redwoods and fir trees, and it appears lushly green in this image. But mixed with these forests are tracts of chaparral (landscapes dominated by fire-adapted, drought-tolerant shrubs and grasses) and large stands of highly flammable knobcone pine.
context_page_description: The Santa Cruz Mountains, part of the Pacific Coast Ranges, are a mountain range in central and northern California, United States. They form a ridge down the San Francisco Peninsula, south of San Francisco. They separate the Pacific Ocean from the San Francisco Bay and the Santa Clara Valley, and continue south to the Central Coast, bordering Monterey Bay and ending at the Salinas Valley. The range passes through the counties of San Mateo, Santa Clara, Santa Cruz, San Benito and Monterey, with the Pajaro River forming the southern boundary.
  The northernmost portion of the Santa Cruz Mountains, north of Half Moon Bay Road, is known as Montara Mountain; the middle portion is the Sierra Morena, which includes a summit called Sierra Morena, and extends south to a gap at Lexington Reservoir; south of the gap, the mountain range is known as the Sierra Azul.
  The highest point in the range is Loma Prieta Peak, 11 miles west of Morgan Hill, with a height of 3,786 feet, near which is the epicenter of the 1989 Loma Prieta earthquake.
context_section_description: The Santa Cruz Mountains have a Mediterranean type climate typical of most of California, with the majority of the annual precipitation falling between November and April. According to the National Weather Service, this totals more than 50 inches (127 cm) annually. Heavy summer fogs frequently cover the western ocean-facing slopes and valleys, resulting in drizzle and fog drip caused by condensation on the redwoods, pines, and other trees, which sustains the moisture-loving redwood forests. Due to a rain shadow effect, precipitation on the eastern side of the range is significantly less, about 25 inches (64 cm) a year. Snow falls a few times a year on the highest ridges, and more rarely the higher valleys receive light dustings.
  The National Weather Service's cooperative weather stations in the mountains have included Black Mountain 2WSW – average annual rainfall 36.65 inches (931 mm), maximum annual rainfall 80.66 inches (2,049 mm), average annual snowfall 0.7-inch (18 mm), maximum annual snowfall 8.0 inches (200 mm); Los Gatos 5SW – average annual rainfall 26.45 inches (672 mm), maximum annual rainfall 103.23 inches (2,622 mm), average snowfall 2.7 inches (69 mm), maximum annual snowfall 9.0 inches (230 mm); and Wrights – average annual rainfall 46.09 inches (1,171 mm), maximum annual rainfall 87.65 inches (2,226 mm), average annual snowfall 1.2-inch (30 mm), maximum annual snowfall 10.6 inches (270 mm). No temperature records were kept at these stations.
  The Santa Cruz Mountains are subject to sharp diurnal temperature fluctuations. The highs and low within a 24-hour period are ~20–30 °F apart on average  but can be as much as 50 °F apart during heat waves depending on location. There is also considerable variation in temperature from day to day in both Summer and Winter with shifting wind directions, and fluctuations in the degree or marine influence.
  Average winter highs range from the low 60's °F (~16–18 °C)  in the coastal valleys to the upper 50's °F (~14–15 °C) in the valleys further inland. Average Winter overnight lows are a function of topology and can vary significantly, from an average low of 37 °F (~3 °C)  in the valleys to ~42–44 °F  (~6–7 °C)  in the thermal belts above the inversion layer where cold air can readily drain off the slopes.
  Thermal inversions occur primarily during the Winter when cool air sinks and gets trapped in the valleys at night, often leading to frost and occasional freezes. Higher elevations above the inversion layer usually stay mild with frost being a rare occurrence. The USDA has recently re-classified the hardiness zones for the higher elevations as USDA 10a to 10b to reflect the lack of frost at those locations. However, while the higher elevations are less prone to frost, they are also more likely to experience occasional snow accumulations. The valleys in contrast are rated USDA 9b with some locations as cold as 9a due to the lack of cold air drainage.
  Summer temperatures regularly reach highs in the 80s °F (~28–30 °C)  with nighttime usually in the upper 40s to lower 60s °F  (~9–18 °C) depending on elevation, distance from the ocean and degree of marine inversion present. Summer weather is dominated by a persistent Marine layer that can vary in depth. When the inversion layer drops below 300–500 feet, the higher elevations are deprived of marine influence and will often be subject to intense heat waves with daytime temperatures in the 95-105F (~35–40 °C) range and extreme low humidity with elevated overnight lows that offer little relief from the heat. Such conditions can lead to fires that can occur even before the official State of California fire season starts in the Fall. Examples of such fires include the 2016 Loma Fire, the 2009 Lockheed Fire and the Summit Fire in 2008 .
caption: Red outlines mark the locations of the Lockheed Fires in the Santa Cruz Mountains.
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