National Park Service recommends climbers be experienced in self-arrest skills, rock climbing, and route-finding. The adjacent Needles are typically regarded as providing better, and somewhat more difficult, mountaineering objectives in the Royal Basin area. Climate Based on the Köppen climate classification, Mount Deception is located in the marine west coast climate zone of western North America. Most weather fronts originate in the Pacific Ocean, and travel northeast toward the Olympic Mountains. As fronts approach, they are forced upward by the peaks of the Olympic Range, causing them to drop their moisture in the form of rain or snowfall (Orographic lift). As a result, the Olympics experience high precipitation, especially during the winter months. 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. In terms of favorable weather, the best months for climbing are June through September. Geology The Olympic Mountains are composed of obducted clastic wedge material and oceanic crust, primarily Eocene sandstone, turbidite, and basaltic oceanic crust. The mountains were sculpted during the Pleistocene era by erosion caused by glaciers advancing and retreating multiple times. See also Olympic Mountains Geology of the Pacific Northwest Geography of Washington (state) List of mountains of the United States List of mountains by elevation References External links Mount Deception weather: Mountain Forecast Mt. Deception photo: Flickr Mountains of Washington (state) Olympic Mountains Mountains of Jefferson County, Washington Landforms of Olympic National Park