<p>Urban forests play a critical role in the health and livability of cities. Global climate change is having significant and wide-ranging impacts on the Earth’s climate and weather patterns. Here, we examine how climate change might affect Brazilian urban forests. Through photo interpretation, we found 6739 urban forest fragments from the 326 cities with a population greater than 100,000 inhabitants. Then, we modelled, using generalized additive model (GAM), generalized linear models (GLM), Maxent, and Random Forest (RF) models, the possible impacts of climate change in urban forests for each Brazilian Biome. Our findings show that climate change, even in more optimistic scenarios, may severely impact the environmental suitability of urban forests in all biomes, that is, the climate will not be suitable anymore for the urban forest types that are now present in the areas studied. This is expected especially in the Atlantic Forest and Cerrado, two biodiversity hotspots. These two most affected biomes house most of the Brazilian human population, one of which tends to suffer substantial impacts. We highlight that Brazilian urban forests can be drastically affected, having their composition extremely modified and their biodiversity may diminish and even face homogenization. Therefore, urgent mitigation and adaptation actions are needed to tackle climate change.</p>