Climate change and HIV are intersecting crises, yet their combined impact on Latin America’s HIV care continuum remains understudied. Using a descriptive cross-sectional design with data from the 2024 Brazilian HIV Stigma Index, we examined the consequences of extreme climate events—primarily the May 2024 floods in Porto Alegre—on healthcare access, mental health, and socioeconomic stability among 156 people living with HIV. These events were associated with substantial care disruptions, with many participants reporting rescheduled or canceled medical appointments and laboratory monitoring. Furthermore, 60.5% reported negative mental health impacts and 37.3% suffered household income reductions. Institutional support reached a minority, leaving many reliant on civil society for survival needs. These findings highlight an urgent need for climate-resilient HIV policies integrating mental health care and social protection to sustain treatment adherence during public calamities.