Significance Climate change may alter the distribution of biomes in tropical regions with implications for biodiversity and ecosystem services. Here we reveal that if the Amazon region becomes drier as predicted, forests may collapse first on seasonally inundated areas due to their vulnerability to wildfires. The widespread distribution of floodplain forests at the western and central regions implies that fire-prone savannas may expand deep into this massive forest biome, threatening the resilience of the entire system. Our findings suggest the need for a strategic fire management plan to strengthen Amazonian forest resilience in the face of climate change.