A large number of realistic weather paths were generated based on output from a single GCM. The simulated weather paths were used to include weather uncertainty in electricity demand forecasting, in order to present a probabilistic electricity demand forecast for Brazil 2016–2100. Annual Brazilian electricity demand will peak around 2060 at about 1071–1200 TWh, and there is significant weather uncertainty, with approx. 400 TWh separating the 10th and 90th percentiles.