In everyday life, people frequently make decisions based on tacit or explicit forecasts about the emotional consequences associated with the possible choices. We investigated age differences in such forecasts and their accuracy by surveying voters about their expected and, subsequently, their actual emotional responses to the 2008 US presidential election. A sample of 762 Democratic and Republican voters aged 20 to 80 years participated in a web-based study; 346 could be re-contacted two days after the election. Older adults forecasted lower increases in high-arousal emotions (e.g., excitement after winning; anger after losing) and larger increases in low-arousal emotions (e.g., sluggishness after losing) than younger adults. Age differences in actual responses to the election were consistent with forecasts, albeit less pervasive. Additionally, among supporters of the winning candidate, but not among supporters of the losing candidate, forecasting accuracy was enhanced with age, suggesting a positivity effect in affective forecasting. These results add to emerging findings about the role of valence and arousal in emotional ageing and demonstrate age differences in affective forecasting about a real-world event with an emotionally charged outcome.