A city installed temperature sensors on lamp posts to map block-by-block heat differences. The denser network revealed cooler pockets near irrigated courtyards that a single weather station had missed. Yet lamp posts are sparse in parks and concentrated along roads, so the map may overrepresent paved environments. The project demonstrates how finer spatial sampling can reveal local variation while also introducing placement bias. It does not estimate heat-related illness or rank all possible cooling interventions.