Forecasts play an important role in planting decisions for Andean peasant producers. Predictions of the upcoming cropping season determine when, where, and what farmers will plant. This research looks at the sources of forecast information used by farmers in three indigenous communities in the Bolivian and Peruvian Altiplano by examining networks used to access weather forecasts. The Altiplano is impacted by the ENSO phenomenon and by frequent droughts and frosts so weather- and climate-related risks are the greatest threats to food security. While both Peru and Bolivia have forecasting systems that widely broadcast forecasts via mass media, farmers do not take them into account when they make production decisions. Instead, they rely on traditional forecasting techniques even though confidence in these indicators is declining. Even though traditional forecast indicators are understood by most producers, few make their own forecasts. Instead they depend upon a few local experts who appear to have little connection to scientific forecasts or agricultural extension agencies. The implications of these findings for improving forecast use are then discussed.