April - October
Denver’s peak season extends from April to October, when the daily high temperature ranges from 40º F in the spring and fall to the upper 80s during summer. Hotel rates don’t vary much by season and there are always deals to be had at local hotels. Hotel rates are more affected by whether or not there’s a large convention in town. These are held at various times throughout the year. Rooms may be especially hard to find during the National Western Stock Show, which runs for several weeks each January. Summer weather in Denver consists of dry heat, although temperatures are rarely scorching. Summer months (June - August) are generally the best times to visit Denver if you're looking to fill your vacation with outdoor activities.
November - February
Denver doesn't have an off season because the ski crowd generally moves in when the fall guests are leaving. Denver weather in winter months (November - February) is chilly with sporadic snowfalls. Although snow generally melts quickly in the city under the persistent Colorado sun, the mountains remain snow-capped all season making it the best time to visit Denver for snow bunnies. Fall is the best time to visit Denver to see the golden Rocky Mountain aspen trees and to experience warm to pleasantly cool, but not too cold, weather conditions.
October - November; March - April
There are two shoulder seasons: from the end of fall to the beginning of the ski season and again during spring run-off—mud season—in the mountains. March is surprisingly the snowiest month in Denver. Spring skiing in the mountains is pleasant and as the snow begins to melt Spring run-off brings flourishing green vegetation and bright flowers to the area, making it one of the best times to visit Denver to appreciate the flora and fauna of the region. It may be possible to find cheaper hotel rates during these times, but again, this depends on what conventions are in town.