Cotopaxi National Park in April

June through September offers the clearest skies and driest conditions. This is peak season, so expect crowds at the popular viewpoints, especially on weekends when Quiteños make day trips. December and January bring another dry window, but afternoon clouds often roll in by noon. If you're planning photos, get to your viewpoints early. The volcano tends to disappear behind clouds by 2 PM most days. Avoid March through May — that's the heavy rainy season. Trails turn muddy, visibility drops to near zero, and the summit climbing season essentially shuts down. October and November are transition months with unpredictable weather, but fewer crowds if you don't mind taking chances with conditions.