Abstract: This study aims to design a route planner functionality that includes real-time context information from physical sensors and citizen observations to support pedestrian navigation in urban areas exposed to extreme heat and floods. Urban population is growing and people living in urban areas are especially exposed to heat and urban flooding, which are two of the anticipated effects of climate change. Route planning functionality can be of value to individual citizens, especially those with limited mobility, as well as for healthcare professionals and authorities who are responsible for crisis response and management. Although the route planner functionality is to be experimentally implemented in a specific tool with the use of broadly available web technologies and real time data, a major generic outcome is the framework that can be used to develop the functionality as part of a decision support tool of any kind.