The influence of expected changes in heat wave intensity during the 21st century on the temperatures of an pre-alpine river are simulated and the mitigating effects of riparian vegetation shade on the radiant and turbulent energy fluxes analysed. Minor stream water temperature increases are modelled within the first half of the century, but a more significant increase is predicted for the period 2071–2100. The magnitude of maximum, mean and minimum stream temperature rises for a 20 year return period heat event was estimated to be in the region of 3 °C. Additional riparian vegetation is not able to fully mitigate the expected temperature rise caused by climate change, but can reduce maximum, mean and minimum stream temperatures by 1 to 2° C. Removal of existing vegetation amplifies stream temperature increases. Maximum stream temperatures could increase by more than 4 °C even in yearly heat events.