Ocean warming poses a significant threat to marine biodiversity, particularly for species with limited capacity to shift their distributions. The Critically Endangered Red Handfish (Thymichthys politus) has undergone substantial population declines and range contraction, with two extant populations now restricted to a single region in southeast Tasmania, Australia. Although coastal warming has been identified as a threat to the species, the potential role of temperature in contributing to the contraction of its distribution over the last ~70 years remains poorly understood. Using remote sea surface temperature (SST) data spanning 1993-2024, we compared thermal conditions among historical and extant red handfish sites and assessed the spatial distribution of cool-temperature environments across Tasmania. Extant populations were associated with substantially cooler winter temperatures than historical sites. Across Tasmania, the two remaining red handfish populations occurred within the coolest 1.3% of coastal areas identified statewide. These findings suggest that this region may function as an important thermal refuge for red handfish and highlight the potential role of cool-water refugia in supporting climate-sensitive marine species. Identifying, protecting, and maintaining such environments may therefore represent an important component of conservation planning under continued climate change.