Weather will likely play an important role when you plan your trip to Colorado, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually December and November, with an average temperature of 24°C, while the coldest months are July and June, with an average of 19°C. The rainiest months in Colorado are January, December, February and October, with each month seeing an average of 234 mm of rainfall.