This study examines the future rainfall regime of Trnava, Slovakia, using downscaled CMIP6 projections validated against local observations. The IPSL-CM6A-LR model and SSP2-4.5 scenario best captured recent conditions, reflecting a moderate-intensifying climate trajectory. Annual precipitation remains largely stable, with a slight wetting trend (~ +3% by 2049). The analysis of extreme precipitation indices (R95p, Rx1day, R20mm) indicates a shift towards more frequent heavy rainfall events and longer wet spells, which will stress the city’s stormwater infrastructure. While annual rainfall totals remain relatively stable, short-duration, high-intensity rainfall events are expected to increase. This study provides a robust, observation-based framework to support adaptive urban drainage design and water management in western Slovakia.