Most weather fronts originate in the Pacific Ocean, and travel northeast toward the Cascade Mountains. As fronts approach, they are forced upward by the peaks of the Cascade Range, causing them to drop their moisture in the form of rain or snowfall onto the Cascades. As a result, the east side of the Cascades experiences less precipitation than the westside of the crest. During winter months, weather is usually cloudy, but due to high pressure systems over the Pacific Ocean that intensify during summer months, there is often little or no cloud cover during the summer.