Weather can change rapidly during all seasons of the year in Yosemite National Park. 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.
It is wise to pack for any season with clothing that can be "layered," ready to peel off or add on as the thermometer dictates. Always include some kind of rain gear when visiting this climate.