Heat waves are a major global public health concern and present a significant challenge to society, especially to underserved populations and those aged 50+, due to their increasing frequency and intensity. They also add significant burdens to the healthcare systems resources, and it has been shown that most deaths occur indoors. Still, our warning systems are based on outdoor temperature measurements. We have developed a real-time indoor temperature alert ecosystem that can capture indoor temperatures that may aid in assessing and responding during a heat wave. We placed ecobee smart thermostats into community housing homes with community housing partners and local health authorities (N = 70), recorded indoor temperature data in near real-time, and administered three surveys during the study period. We investigated: (i) indoor temperatures trends during the heatwave season of 2022 in Vancouver and Ottawa, Canada; (ii) behaviours of participants during this period; (iii) housing characteristics; (iv) delivery of time-sensitive temperature alerts to enable check-ins on participants, and (v) perceptions to heat risk and methods of communication. Initial results shows different observations that includes: a) unsafe indoor temperatures were reached and persisted (above 26°C and 31°C) despite a milder heat wave season than the previous year (in BC); b) gaps in understanding of best practices to stay safe exist; c) home characteristics increase risk of overheating; d) coordinating with community housing to check-in can protect individual health; and e) ensure individuals are protected during extreme heat events. Results suggest that implementing indoor temperature provides vital information to inform heat health response plans. The smart thermostat technology can be retrofitted into homes in Canada as it is commercially available. This study presents a scalable solution for monitoring indoor temperatures. It demonstrates how smart thermostats can monitor indoor temperature exposure conditions to prevent deaths during extreme heat events.