Mountain Forecasts for the major Nevadas & Peaks in the Cusco region.
Below are links to some of the popular mountain routes in the Peruvian Andes. These are intended to be a guide only, as weather is an incredibly variable element to pinpoint. Especially in the Andes where it is believed that weather patterns have changed rapidly in the last few years; thus making it harder to accurately provide mountain forecasts further than a few weeks out.
Weather temperature and condition is also proportional to the altitude you find yourself at. There is a direct correlation to the higher you climb or ascend in the mountains; the more susceptible you are likely to be to a change in adverse weather conditions.
The climate of Peru is very diverse, with a large variety of climates and microclimates, including 28 of the 32 world climates. Such a diversity is chiefly conditioned by the presence of the Andes mountains and the cold Humboldt Current.
Climate on the coast is arid and semi-arid with high temperatures and very little rainfall. The Andes mountains observe a cool-to-cold climate with rainy summers and very dry winter. The eastern lowlands present an Equatorial climate with hot weather and rain distributed all year long.
In the Peruvian Andes (clima de Sierra in Spanish) exhibits the largest diversity among the country. Temperature is proportional to altitude, varying from temperate (annual average of 18 °C or 64 °F) in the low-lying valleys to frigid (annual average below 0 °C or 32 °F) in the highest elevations. The maximum temperature is often steady throughout the year, the low varying due to the presence of clouds in the rainy season; which help keeping to some extent the daytime heat during the night. In the absence of clouds, nights are much colder.
There is some excellent and detailed information on Wikipedia which explains more about the weather patterns and mountain forecasts in the Peruvian Andes of Cusco.