Sierra Nevada (U.S.) - Climate and Meteorology

Climate and Meteorology

The climate of the Sierra Nevada is influenced by the Mediterranean climate of California. During the fall, winter and spring, precipitation in the Sierra ranges from 20 to 80 in (510 to 2,000 mm) where it occurs mostly as snow above 6,000 ft (1,800 m). Summers are dry with low humidity; however, afternoon thunderstorms are common, particularly during the North American Monsoon. Summer high temperatures average 42–90 °F (6–32 °C). The growing season lasts 20 to 230 days, strongly dependent on elevation.

The Sierra Nevada snowpack is the major source of water and a significant source of electric power generation in California. Many reservoirs were constructed in the canyons of the Sierra throughout the 20th century, Several major aqueducts serving both agriculture and urban areas distribute Sierra water throughout the state. However, the Sierra casts a rain shadow, which greatly affects the climate and ecology of the central Great Basin. This rain shadow is largely responsible for Nevada being the driest state in the United States.

The height of the range and the steepness of the Sierra Escarpment, particularly at the southern end of the range produces a wind phenomenon known as the "Sierra Rotor". This is a horizontal rotation of the atmosphere just east of the crest of the Sierras, set in motion as an effect of strong westerly winds.