Montana Climate (Pg. 2)
Average annual precipitation is 15 inches (380 mm), but great variations are seen. The mountain ranges block the moist Pacific air, holding moisture in the western valleys, and creating rain shadows to the east. Heron in the west receives the most precipitation, 34.70 inches. On the east side of a mountain range the valleys are much drier; Lonepine averages 11.45, and Deer Lodge 11.00 inches of precipitation. The mountains themselves can get over 100 inches (2,500 mm), for example the Grinnell Glacier in Glacier National Park gets 105 inches (2,700 mm). Perhaps the driest is an area southwest of Belfry that averaged only 6.59 inches (167 mm) over a 16 year period. Most of the larger cities get 30 to 50 inches (1,300 mm) of snow each year. Mountain ranges themselves can accumulate 300 inches (7,600 mm) of snow during a winter. Heavy snowstorms can occur as early as September or as Late as May, but most snow falls from November to March.
The climate has become warmer in Montana and continues to do so. The glaciers in Glacier National Park have receded and are predicted to melt away completely in a few decades. Many Montana cities set heat records during July 2007, the hottest month ever recorded in Montana. Winters are warmer, too, and have fewer cold spells. Previously these cold spells had killed off bark beetles which are now attacking the forests of Western Montana. The combination of warmer weather, attack by beetles, and mismanagement during past years has led to a substantial increase in the severity of forest fires in Montana.
