Urban Heat Islands (UHI) pose a significant challenge for tropical cities, especially as global temperatures continue to rise. Despite the prevalence of this problem, medium-sized cities in tropical regions remain underrepresented in UHI studies compared to large cities in temperate climates. This study aimed to characterize the UHI effect in a rapidly growing medium-sized city in a tropical region, which has experienced unplanned urban sprawl. Temperature data were collected using data loggers in ten distinct areas of the city. The results revealed a pronounced UHI effect, with higher intensities in the city center and lower intensities in areas with native vegetation. During the dry season, extreme UHI effects (>
6 °C) were observed 10% of the time, with strong UHI effects (4 °C-6°C) present 50% of the month. In contrast, during the wet season, moderate UHI effects (2 °C-4°C) were recorded only 15% of the time. A strong correlation was identified between land use, particularly vegetation cover, and UHI intensity. This study not only sheds light on the dynamics of UHI in this specific tropical city, but also offers relevant insights for other mid-sized cities in similar tropical contexts around the world. The findings provide valuable knowledge for the development of adaptation and mitigation strategies in urban planning, which can be applied globally to cities facing rapid urbanization in hot climates. Furthermore, this research contributes to the advancement of UHI analysis methodologies that can be replicated in tropical and temperate cities, building on previous studies conducted in Brazil and other regions of the world.