This technical note is aimed primarilyat professionals in national meteorological and hydrologicalservices (NMHSs), who are trying to improve the quality andrelevance of their services to match their societies’growing needs for meteorological and hydrologicalinformation. At the same time, the note serves as a usefulresource for the experts and teams involved in theactivities and projects that tackle various aspects oftransforming hydromet services. It provides insight intosome of the technical challenges that NMHSs face andsuggests approaches to addressing these challenges. Theobjective of this note is to bring attention to thesetechnical issues to better understand them and prioritizethe potential solutions.