Snowpack conditions in California vary across different mountain ranges that supply snow for the state's water resources. The Sierra Nevada range is a crucial source, with snowpack providing nearly one-third of the state's water supply. The snowpack in the Sierra Nevada is measured by the California Department of Water Resources via manual surveys and electronic sensors known as snow telemetry (SNOTEL) sites. Other mountain ranges, such as the Cascades and the Siskiyou Mountains, also contribute to California's snowpack.

Snowpack runoff from these mountains feeds into several important rivers and watersheds, including the Sacramento River, San Joaquin River, and the Colorado River. These watersheds supply water for agriculture, drinking water, and hydroelectric power.

California's winter climate is characterized by periodic storms known as "atmospheric rivers," which bring heavy precipitation and contribute to snow accumulation. However, climate change poses a threat to the state's snowpack, as rising temperatures may lead to more rainfall than snowfall, altering the timing and quantity of water supply.

Interesting facts about snow science and history in California include the development of advanced techniques to measure snowpack, such as airborne laser scanning (LiDAR), which provides detailed information about the snowpack's depth and density. Additionally, the 2015 snowpack was historically low, reaching only 5% of the average due to severe drought conditions. Overall, accurate and up-to-date information on snowpack conditions is crucial for managing California's water resources effectively.