| Mountain Climate It is often said that in tropical mountain ranges, rather than four seasons in the year, there are four seasons in a day. Mornings in the Peruvian Andes are bright but cool like in springtime. The day heats up through noon when, like in summer, many head for the shade. In the afternoon, cumulus clouds that appeared in the sky during the morning hours reach their climax, and the oblique rays of the sun make it feel like autumn. After the usually short sunset, a winter cold sets in. Such varied weather patterns result from the location of the Andes, which run from north to south and separate the warm and humid Amazon basin winds from the masses of cold wind blowing from the Pacific Ocean. Due to their tropical location, the Peruvian Andes feature well-defined rainy and dry seasons with an almost imperceptible transition period between the two. Also, due to Peru’s location in the Southern Hemisphere, seasons are reversed compared to Europe and the United States. May to September Winter or the dry season is the only season open to high mountain climbing. Proximity to the Equator means shorter days by 30 to 50 minutes as the season moves on. Frosts occur above 4,500 masl. July offers the best weather, before the cold northern winds start blowing in August. September to December A season suitable for climbing lower glaciers and trekking, it is similar to spring in the Northern Hemisphere. Afternoon showers and an occasional electric storm become more frequent as cumulus clouds dump off their morning humidity in a matter of minutes. Skies are then clear before night falls and the skies become studded with stars. December to May A season of torrential afternoon storms, and occasional light, persistent drizzle, this is not an appropriate time for mountaineering expeditions in the Andes. On a rainless day, a walking tour may be possible along a gully, although streams, almost dry in winter, can become impossible to cross during this time of the year. |