Climate

Yosemite has a Mediterranean climate, with most precipitation falling during the mild winter, and the other seasons are nearly dry (less than 3% of precipitation falls during the long, hot summers). Because of orographic lift, precipitation increases with elevation up to 8,000 feet (2,400 m) where it slowly decreases to the crest. Precipitation amounts vary from 36 inches (910 mm) at 4,000 feet (1,200 m) elevation to 50 inches (1,300 mm) at 8,600 feet (2,600 m). Snow does not typically persist on the ground until November in the high country. It accumulates all winter and into March or early April.

Mean daily temperatures range from 25 °F (−4 °C) to 53 °F (12 °C) at Tuolumne Meadows at 8,600 feet (2,600 m). At the Wawona Entrance (elevation 5,130 feet or 1,560 metres), mean daily temperature ranges from 36 to 67 °F (2 to 19 °C). At the lower elevations below 5,000 feet (1,500 m), temperatures are hotter; the mean daily high temperature at Yosemite Valley (elevation 3,966 feet or 1,209 metres) varies from 46 to 90 °F (8 to 32 °C). At elevations above 8,000 feet (2,400 m), the hot, dry summer temperatures are moderated by frequent summer thunderstorms, along with snow that can persist into July. The combination of dry vegetation, low relative humidity, and thunderstorms results in frequent lightning-caused fires as well.

At the park headquarters, with an elevation of 3,966 feet (1,209 m), January averages 38.2 °F (3.4 °C), while July averages 73.0 °F (22.8 °C), though in summer the nights are much cooler than the hot days. There are an average of 39.5 days with highs of 90 °F (32 °C) or higher and an average of 97.9 nights with freezing temperatures. Freezing temperatures have been recorded in every month of the year. The record high temperature was 115 °F (46 °C) on July 20, 1915, while the record low temperature was −6 °F (−21 °C) on January 2, 1924 and on January 21, 1937. Average annual precipitation is nearly 37 inches (940 mm), falling on 65 days. The wettest year was 1983 with 68.94 inches (1,751 mm) and the driest year was 1976 with 14.84 inches (377 mm). The most precipitation in one month was 29.61 inches (752 mm) in December 1955 and the most in one day was 6.92 inches (176 mm) on December 23, 1955. Average annual snowfall is 65.6 inches (1.67 m). The snowiest year was 1967 with 154.9 inches (3.93 m). The most snow in one month was 140.8 inches (3.58 m) in January 1993.