- Montana's geography can be split into two basic regions: the mountains, which lie in the west, and the prairies, which encompass the eastern portion of the state. The Continental Divide separates the two regions, leading through western Montana from north to south, and forming the southwestern border of the state.
Copyright: - US National Park Service
Glacier National Park
Several mountain ranges form the western portion of Montana. In general the northern mountains were formed by glaciation and the southern formed through volcanic activity. Glacier National Park lies in this region near the Canadian border and straddling the Continental Divide. Western Montana also harbors most of the National Forests in the state, as well as the northern most portion of the Continental Divide Trail in the United States. The southwestern quadrant contains a slim portion of Yellowstone National Park, which includes three entrances.
From the Continental Divide eastward is primarily prairie, although several isolated mountains ranges complete the landscape of central Montana. Immediately east of Helena are the Lewis and Clark and Helena National Forests. The terrain within these areas include rugged mountains, canyons and gorges, as well as rolling hills. South central Montana also contains mountainous terrain.
Eastern Montana contains the Missouri and Yellowstone River Valleys in the north and south respectively. These rivers provide much needed water to this otherwise arid region. The Missouri has been dammed in several places. One such place has created the Fort Peck Reservoir, which is surrounded by the C.M. Russell National Wildlife Refuge. The Yellowstone River is dam free and flows through the southeastern portion of Montana and into Yellowstone National Park.
Recreation - Montana contains recreation opportunities for every interest and ability. Highlights in the state include long-distance backpacking on the Continental Divide Trail, hiking in Glacier National Park, wildlife viewing in 16 wilderness areas and boating on Fort Peck and Bighorn Canyon Reservoirs.
Climate - The climate in Montana varies with the terrain. The western region of the state receives storm systems from the Pacific Ocean, which tend to be temperate. Because of its mountainous topography the region receives significant snowfall amounts, with winter temperatures usually below freezing.
Summer in this region is mild with high temperatures reaching 85 degrees F. Nights are cool in the mountains during the summer. Bring warm layers, hats and gloves if camping. High country roads usually do not open until mid to late June, due to snow accumulation. Thunderstorms are a daily occurrence in June, July and August, so be prepared for rain in the mountains.
The eastern plains of Montana generally experience more dramatic weather patterns than the west. Summer temperatures reach 100 degrees F in many areas. May and June are normally the rainy months of the year, but summer brings thunderstorms almost daily. Winter weather is also extreme in this region. Cold winds blow from the north creating a severe wind-chill factor. Snow usually doesn't accumulate on the prairies, because most of the moisture is absorbed by the western mountains.