Population dynamics and fishery productivity of South Australian Snapper are fundamentally driven by highly variable inter-annual recruitment. This study examined the environmental factors influencing recruitment variability in South Australian Snapper stocks and evaluated the potential impacts of climate change on future stock productivity. Analysis of four decades of recruitment and environmental data from the Spencer Gulf/West Coast, Gulf St Vincent, and South-East stocks found no single environmental variable that consistently explained annual recruitment variation, highlighting the complex interplay of biological and environmental processes that drive recruitment success. However, spawning activity was strongly associated with a relatively narrow sea surface temperature range (18–22.5°C), indicating that successful reproduction and early life-stage development occur within specific thermal conditions. Over the past two decades, sea surface temperatures in the northern gulfs have increased by 1.5–2.0°C, while marine heatwaves have become more frequent and intense, reducing the duration of favourable spawning conditions and coinciding with long-term declines in recruitment in Spencer Gulf and Gulf St Vincent. Climate projections under the SSP2-4.5 scenario indicate that continued warming could reduce the availability of optimal spawning temperatures by approximately 70% by the mid-2040s, potentially increasing the likelihood of recruitment failure and limiting population productivity. Although the mechanisms linking environmental change to recruitment remain uncertain, these findings suggest that climate-driven warming may further constrain the resilience and recovery potential of South Australian Snapper stocks, reinforcing the importance of continued monitoring, adaptive fisheries management, and targeted research to improve our understanding of recruitment processes under a changing climate.