With heatwaves rising in frequency and severity, and already estimated to kill more than 350,000 people per year globally, adapting our cities for a hotter future is crucial. Fortunately, innovative data collection methods can equip city leaders with knowledge of current and future heat exposure while building citizen support for action. This session will exchange experiences of mapping and modeling extreme heat exposure using an engaging interactive approach. Participants will demonstrate how Johannesburg, South Africa and Bandung, Indonesia organized volunteer-driven heat mapping campaigns. We will highlight the insights about ‘who is exposed’ to heat (including disparities between neighborhoods) and future evolution of heat stress (including fine-grained urban projections using the UrbClim model). The facilitators will engage session participants in using three types of sensor: phone-mounted thermal infrared cameras, hand-held temperature and humidity monitors, and sensors mounted on motorbike handlebars. The session will raise awareness of participatory heat mapping approaches and modeling techniques to create robust scientific datasets as a basis for city heat action plans.