Cycling, as a very attractive green form of transportation, is also one of the most sustainable. Electric bicycles, the most popular electric vehicles, subscribe to this type of transportation, being highly environmentally friendly. They have several advantages when compared to traditional bicycles, but also a weak point in terms of long battery (re)charging duration. Consequently power-saving solutions for electric bicycles are of high research interest. In this context, this paper proposes a novel energy-efficient weather-aware route planner (eWARPE) for electric bicycles. The solution makes use of the weather information in order to recommend the optimal departure time that allows the cyclist to avoid the adverse weather conditions and to maximize the energy savings of the electric bicycle. Note that the departure time is in a user-configurable time interval. The departure time can be recommended for a preferred route introduced by the user or for a route built in eWARPE based on user input. The proposed solution was validated through numerical analysis. Moreover, a survey was conducted in order to assess the impact of the adverse weather conditions on cyclists and to measure how the cyclists will benefit from the proposed solution.