Although Voice Assistants are ubiquitously available for some years now, the interaction is still monotonous and utilitarian. Sound design offers conceptual and methodological research to design auditive interfaces. Our work aims to complement and supplement voice interaction with sonic overlays to enrich the user experience. Therefore, we followed a user-centered design process to develop a sound library for weather forecasts based on empirical results from a user survey of associative mapping. After analyzing the data, we created audio clips for seven weather conditions and evaluated the perceived combination of sound and speech with 15 participants in an interview study. Our findings show that supplementing speech with soundscapes is a promising concept that communicates information and induces emotions with a positive affect for the user experience of Voice Assistants. Besides a novel design approach and a collection of sound overlays, we provide four design implications to support voice interaction designers.