Montana is known for its unpredictable weather. The weather maintains as much variety as does the state's topography. The lowest temperature recorded in the lower 48 states was -70F recorded northwest of Helena. Hot summers are common; 117 degrees has been recorded in both Glendive and Medicine Lake, but the hottest day in Montana is not suffocating due to its low humidity which generally ranges between 20 and 30 percent. The real beauty of Montanas weather is that it is very dry. Extremes of hot or cold never feel oppressive as a result.
May and June are the wettest months for most of the state. The average rainfall is 15 inches, which can vary from less than 10 inches on the plains and to more than 50 inches in the mountains. July and August are usually Montanas warmest, driest periods and serve as the busiest time for tourism and recreation. Often there is a pleasant Indian summer in September and October. Warm, bright days with cool nights make it an exhilarating time with fishing at its prime. During the fall, Montana's forests may not flaunt the vibrant colors of the eastern woodlands, but its tamaracks are bright yellow contrasting nicely against the evergreens, and the aspen groves turn a dazzling gold.
The infamous Montana winter rarely settles in for keeps. Even though snow can fall in July, roads can also be clear throughout November. Montana's cold spells and blasts of arctic air bring blizzards which often melt the following week from dry chinook winds blowing from the west. (Native Americans called these winds the snow eaters.) Even when roads are clear, travelers must be careful as one could hit a patch of ice in a shaded, mountainous area although the road may be dry for miles. While temperatures can be extreme in Montana, the low humidity never causes the weather to be oppressively hot or cold.