In the southern Peruvian Andes, communities are highly dependent on climatic conditions due to the mainly rain-fed agriculture and the importance of glaciers and snow melt as a freshwater resource. Longer-term trends and year-to-year variability of precipitation or temperature severely affect living conditions. This study evaluates seasonal precipitation and temperature climatologies and trends in the period 1965/66–2017/18 for the southern Peruvian Andes using quality-controlled and homogenized station data and new observational gridded data. In this region, precipitation exhibits a strong annual cycle with very dry winter months and most of the precipitation falling from spring to autumn. Spatially, a northeast–southwest gradient in austral spring is observed, related to an earlier start of the rainy season in the northeastern part of the study area. Seasonal variations of maximum ...

The rainy season is of high importance for livelihoods in the Southern Peruvian Andes (SPA), especially for agriculture, which is mainly rain fed and one of the main income sources in the region. Therefore, knowledge and predictions of the rainy season such as its onset and ending are crucial for planning purposes. However, such information is currently not readily available for the local population. Moreover, an evaluation of existing rainy season indices shows that they are not optimally suited for the SPA and may not be directly applicable in a forecasting context. Therefore, we develop a new index, named Climandes index, which is tailored to the SPA and designed to be of use for operational monitoring and forecasting purposes. Using this index, we analyse the climatology and trends of the rainy season in the SPA. We find that the rainy season starts roughly between September and Janu...

In the southern Peruvian Andes, climatic threats such as water scarcity or frost pose major challenges for agriculture. Such events may result in severe yield losses threatening the livelihood of smallholder farmers due to missing adaptive and coping strategies. Knowledge on climate variability and change, on the current state of the climate, as well as short- to midrange predictions potentially improve the farmers’ risk management. However, such knowledge is only partly available and often does not reach rural communities. Climandes, a pilot project of the Global Framework for Climate Services, tackled these shortcomings through the enhancement of climatological observations, the production of gridded datasets using satellite and station observations, the verification of seasonal forecasts to determine their usefulness for small-scale applications, and through the establishment of com...