Fostering an iterative learning culture for climate services: A case study of the agro-climatic bulletins approach in Vietnam's Mekong River Delta

Tailoring climate information to end users' specific needs has gained prominence in the climate services literature and policy, reflecting a growing recognition of the value of iterative, participatory engagement. This study evaluates the outcomes of the Agro-Climatic Bulletins (ACBs) in the Mekong River Delta (MRD) of Vietnam, for, and according to, the actors in charge of tailoring climate information to end user's needs. Initiated as a pilot in 2020 to enhance farmers' agricultural resilience by providing timely, location-specific climate information, the ACB approach has evolved into a multidimensional tool that integrates hydrometeorological and agricultural data for localised advisories. Its rapid expansion across the MRD reflects institutional commitment as well as the role of Vietnam's centralised governance architecture. Drawing on 33 in-depth interviews with institutional stakeholders, the study identifies 22 outcomes across five domains: practice, communication, capacity, interaction and scaling, showing the emergence of a learning culture characterised by iterative learning loops and adaptation. Operationally, ACBs have supported agricultural planning and service delivery, enhanced communication and improved their usability through digital and localised formats. Institutionally, the approach has strengthened technical capacity and inter-agency collaboration and trust. While local resource mobilisation supported approach scaling, challenges remain in securing sustainable funding across governance levels, in formalising the mandates of the actors involved and addressing constraints for technical service delivery. Our study highlights the importance of embedding climate information services within institutional mandates and policy frameworks to allow intermediary actors to achieve timely, useful and accessible information tailored to user's needs. Fostering an iterative learning culture is essential to ensure responsiveness to evolving agro-ecological conditions and stakeholder needs, and transform climate services into dynamic platforms for agricultural resilience.