In 2013 the World Health Organization (WHO) published the report Protecting health from climate change: vulnerability and adaptation assessment. The aim was to provide basic and flexible guidance on conducting national or subnational assessments of current and future vulnerability (the susceptibility of a population or region to harm) to the health risks of climate change, and of policies and programmes that could increase resilience, taking into account the multiple determinants of climate-sensitive health outcomes. That guidance has been a very useful tool, applied to more than 50 countries and settings, and has helped countries to prepare their health contributions to United Nations Framework Convention on Climate Change national adaptation plans. Since the launch of the guidance, WHO, technical partners such as Health Canada, and countries have learned much in terms of its applicability in different countries, at national and local levels. At the same time, knowledge on climate change and health has increased. WHO, the Pan American Health Organization and Health Canada have produced this updated version, which aims to better support countries in their assessments by proposing a simpler tool that incorporates all lessons learned.