Climate change impacts represent threats to the population worldwide, and the health sector which is responsible for taking care of their life and health will also be impacted. While the consequences of these impacts are imminent, little or nothing has been done by the health sector at national and sub-national levels worldwide to prepare to respond to them. Therefore, health adaptation planning in regard to climate change is crucial to building climate-resilient health systems. This research aims to propose an approach containing phases and steps for developing a Health Adaptation Plan at a sub-national level. The methodology involved the collection and analysis of several guidelines and tools provided by the WHO and other relevant organisations,. This is supplemented by analysis of existing Health Adaptation Plans at national and subnational levels developed in different governmental organisations and systems worldwide since 2003. The findings included four phases and twelve steps for developing Health Adaptation Plans at subnational- level organisations in the health sector. This establishes guidance for subnational organisations within the health sector that are planning to develop a Health Adaptation Plan