ExTrass seeks to better prepare medium-sized and large cities in Germany for heavy rainfall and heat. To this end, restraining and enabling factors of urban climate adaptation are analysed and successfull measures are identified. A large part of the project work is undertaken in three case study cities: Potsdam, Remscheid and Würzburg. Here, among other things, the project team tests greening measures, works towards climate-sensitive urban planning, contributes data on city climate, educates the population on risks and improves contingency plans. In addition, opportunities for exchange are created so that cities can better learn from each other.