Climate information services (CIS) involve the production, translation, transfer, and use of climate information for individual and societal decision-making. After years of focus on building CIS around available information, today the CIS community recognizes that effective CIS are aimed at specific users of the service and their particular needs. In this review, we describe practical experiences identifying CIS users and their needs, showing different approaches, assumptions, and levels of empirical support. Our uneven and limited understanding of users and their needs presents four key challenges for climate services: (1) designing effective assessments of users and their needs, (2) identifying and overcoming barriers to CIS use, (3) scaling up a CIS and (4) the cross-cutting challenge of dealing with changing conditions and changing user knowledge. Reviewing project and academic literature on CIS in sub-Saharan Africa, we assess what is known and not known relating to these challenges. We prioritize identified gaps in knowledge into a learning agenda to organize learning from practice and research such that both serve a range of needs for knowledge about users and their needs, speak to current ‘good practices’ in CIS design, management, and evaluation, and point the way to better practices in the future.