In the West African Sahel, climate variability and climate change pose huge challenges to food security and health, particularly for poor and marginalised population groups. Co-production of actionable climate information between scientists and users has been advocated to increase its use in adaptation to climate change. Consequently, Weather and Climate Services (WCS) co-production models have been expanding, but there have been few evaluations of their effects, and those that exist mostly focus on the end user. The empirical contribution of this paper is an evidence based evaluation of the scaling of WSC co-production models and its enabling factors. The methodological contribution is a systemic and iterative evaluation method involving multiple analytical tools. The scaling of WCS in Senegal involved at least 161 actors and resulted in five axes of transformation: 1) continuous improvement of WCS, 2) emergence and consolidation of WCS facilitators, 3) inclusion of WCS in action planning, 4) active mobilisation to sustain WCS scaling, and 5) empowerment of actors. New users and uses emerged beyond agriculture, involving the fisheries, water and energy sectors, producing changes in institutional communication strategies, operational planning, and in coordination between actors. Enabling factors for scaling included capacity strengthening, knowledge-sharing and action platforms, interaction opportunities, and financial and political support. However, reduced precision of forecasts over time is perceived. New challenges are emerging including improving delivery and finer grain information, getting the private sector involved, and building capacity and trust at a large scale, to keep pace with the increase in uses and users.