Climate change presents a pervasive global threat to billions of people as well as ecosystems. Global mitigation policy failures mean we must now urgently adapt to projected climate impacts. While local government is expected to play a vital role in climate change adaptation, major breakdowns are occurring in local governments’ ability to implement adaptation responses. Studies point to the importance of two key factors underpinning successful municipal climate change adaptation – supportive leadership and an authorising environment for adaptation. But few studies provide in-depth analysis of these factors and how they play out in practice. This paper reports the results of research addressing this knowledge gap, drawing on analysis of leadership in four Australian local governments (municipal councils). Twenty-five local government elected officials, executive leaders, and staff required to operationalise leaders’ decisions were interviewed. Interviews examined leaders’ role and influence in climate change adaptation and their receptiveness to mainstreaming. Results show that whether leaders consider climate risk on their policy agenda is highly variable and subject to factors such as: public mood and community expectations; issue salience; the presence of dedicated policy entrepreneurs to champion a response; and focusing events that heighten the urgency of adaptation. We identify three concrete opportunities to mainstream municipal climate adaptation responses: enhance issue salience within leaders; leverage networks of influence; and strengthen formal systems of municipal climate governance.