The planet is currently undergoing rapid and substantial change, but, across the globe, people’s health is not affected evenly by the impacts of climate change. Poverty and marginalization mediate the relationship between climate change and human health, meaning that potential adverse human health outcomes are not an inevitable consequence of climate change. Rather, they result from a culmination of political decisions, which are routinely made far away from and without the people most affected, without much understanding of or interest in their perceptions and lived experiences, or the varied local changes that affect their health. Local early warning systems, incorporating anticipatory action and response capacities, hold the potential to empower communities to reduce their health risks, but marginalized communities are routinely left out of decision-making, making these systems prone to failure. This research investigates health disaster risks and methods for building inclusive community-based early warning and response systems in three extreme low-resource, conflict-affected, and climate change-impacted communities in Kenya. By working together with community health leaders, this coproduced research identifies how communities conceptualize their place-based and positive health, which encompasses understandings of health beyond the absence of disease and recognizes the fundamental interdependence and collective nature of health. Through this lens, we use participatory methods to identify how health challenges, including climate change, impact the social and environmental determinants of health, and how these changes can effectively be measured, monitored, and acted upon. This research asserts the importance of taking a “first-mile approach”, where communities meaningfully participate in every part of the early warning system process, including contributing their understanding of health and health risks, observations and monitoring, preparedness and response, and communication of early warnings. Improving early warning systems for health in complex settings is essential to close the climate change-human health justice gaps, and it is also pivotal for global health security given that such settings are often zones of disease emergence and re-emergence.