Weather can change rapidly during all seasons of the year. Elevation plays a major role in temperature and precipitation. Most of the moisture comes in the months of January, February and March, and the winter climate is relatively mild. Sierra summers are typically warm and dry. April and November are transitional months, when warm, sunny days can suddenly become stormy.
Clouds can build up during the summer to produce spectacular thunderstorm activity.
Always include some kind of rain gear. The Tioga Pass entrance is closed from the first major snowstorm in November until approximately early June due to snow. The roads entering the park on its west side are kept open all year, but may require tire chains because of snow anytime between November and April. Several airlines serve Fresno Air Terminal and United Express serves the Merced airport. Motor coach transportation is available year- round from Merced Amtrak station and Transportation Center to Yosemite Valley.