Weather and Climate: Yosemite National Park is a changing environment where weather can vary by the minute, with increased chances of change at higher elevations. Temperatures at the 4,000-foot Yosemite Valley can rise to more than 100°F in the summer with lows in the 20s and nearly 30 inches of snowfall, on average. Lightning, common in the summer, is an essential element in the Sierra Nevada fire-dependent environment. Since 1972, lightning ignited 1,800 fires in Yosemite; a third of those were managed by park staff. Overall, the changing weather only adds to the enjoyment of Yosemite, luring visitors during all four seasons.