The existence and severity of climate change are supported by overwhelming scientific consensus and recognized as among the most serious threats facing humanity. Nevertheless, conspiracist narratives continue to flourish globally, attracting multidisciplinary attention. These include denialist narratives which delegitimize the threat of climate change, and warmist narratives which reaffirm or exaggerate it. Despite a research boom in recent years, most studies on the psychology of conspiracy theories remain focused on WEIRD populations, leaving underrepresented regions, disproportionately vulnerable to climate impacts, largely overlooked. The current research addressed that gap by focusing on the Caribbean, an archipelago of small-island developing states along the northern coast of South America. Across three studies, we examined the relationships between climate change conspiracy beliefs, perceptions and behaviours in the aftermath of extreme weather events in Grenada (N = 145) following Hurricane Beryl, and in Trinidad and Tobago (N = 417) and Barbados (N = 206), both facing increasingly volatile rainy and dry seasons. We also assessed whether conspiracy beliefs were linked to migration intentions and attitudes toward climate migrants. Findings indicate that personal experience with extreme weather predicted stronger warmist, but not denialist beliefs. Both forms of conspiracy beliefs were consistently associated with climate-related perceptions and policy attitudes. Specifically, denialist beliefs negatively predicted, and warmist beliefs positively predicted, subjective attribution of weather events to climate change, adaptation policy support, and sustainable investing. No conclusive evidence emerged for links to disaster preparedness intentions. Regarding migration, conspiracy beliefs did not predict migration intentions but were associated with attitudes toward climate migrants. Specifically, denialist beliefs were negatively associated, and warmist beliefs positively associated, with support for climate migration policies and favourable attitudes toward climate migrants. This research is the first to examine climate change conspiracism in the Caribbean, highlighting associations with perceptions, attitudes, and behaviours in extreme weather contexts.