Maps are an important tool for communicating natural hazard risks and motivating protective action. Their effectiveness, however, depends on how users perceive and interpret the information presented, making careful design and empirical evaluation essential. This study describes an iterative, co-designed and evaluation process of prototype natural hazard risk maps developed for the Canton of Lucerne, Switzerland. It involved focus group discussions and an online survey of 193 residents. The results indicate that the colour scheme had no significant effect on map comprehension, suggesting that a rigorous, user-centred design process can produce robust and effective maps. Instead, individual characteristics, particularly homeownership, which is associated with higher age, and perceived map quality emerged as stronger predictors of comprehension. Exposure to the maps also led to a measurable increase in spatial risk perception, demonstrating that risk maps can serve as effective communication tools in their own right. Based on these findings, we recommend embedding risk maps within broader, participatory communication strategies, and structuring information in a layered manner to accommodate different levels of expertise and user needs.