Summer is a busy time. Hotels in tourist destinations book up early, especially in July and August. Denver summertime highs above 100°F are not uncommon, and the winters are still cold, with highs in the 20s and 30s at the height of winter. The entire state sees snowy winters, even on the plains -- where some of the most powerful blizzards hit. Colorado has a reputation for extreme weather, to be sure, but that cuts two ways: no condition ever lasts for long.
If you don't mind capricious weather, spring and fall are opportune seasons to visit. Rates drop and crowds are nonexistent. Spring's pleasures are somewhat limited, since snow usually blocks the high country -- and mountain-pass roads -- well into June. But spring is a good time for fishing, rafting on rivers swollen with snowmelt, birding, and wildlife-viewing. In fall, aspens splash the mountainsides with gold, and wildlife come down to lower elevations. The fish are spawning, and the angling is excellent.
Summer in the Rocky Mountains begins in late June or early July. Days are warm, with highs often in the 80s; nighttime temperatures fall to the 40s and 50s. Afternoon thunderstorms are common over the higher peaks. Fall begins in September, often with a week of unsettled weather around mid-month, followed by four to six gorgeous weeks of Indian summer -- frosty nights and warm days. Winter creeps in during November, and deep snows arrive by December. Temperatures usually hover near freezing by day, thanks to the surprisingly warm mountain sun, dropping considerably overnight, occasionally as low as -60°F. Winter tapers off in March, though snow lingers into April on valley bottoms and into July on mountain passes.
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