Climate & Best Seasons
The Peruvian Andes are subject to conflicting weather influences coming both from the Pacific Ocean and from the jungle. Traditionally there is a "dry" and "rainy" season.
Generally, the months with more settled weather are May until September, with shoulder periods in mid-April and late September to October. However, world climatic changes are affecting weather patterns in Peru. Periods of cloud and rain during what were traditionally the driest months are possible.
Mountaineering Specifics: For 5000m and non-technical peaks, the optimal window is May to September. 6000m and highly technical peaks can generally only be climbed safely from mid-June to August, as conditions stabilize.