Credibility is a critical issue in climate policy for helping to allocate public funding and private investments, and for implementing, mainstreaming and catalysing climate policy. In the context of urban climate adaptation policy, we define credibility as the likelihood of local adaptation plans being successfully implemented and sustained in the long-term. We examine the credibility of local adaptation policies based on three key areas: policy and economic credibility, scientific credibility and legitimacy. Within these three areas, we look at resources, reliability, public and private support, creation of usable knowledge, monitoring, evaluation & reporting (MER), adaptive management, transparency, participation, equity and justice. For each of these components, we define a set of metrics and test it in 20 Spanish cities, a representative sample to capture diversity of a highly decentralised country. Systematic review protocols have been applied to identify adaptation policies and measures. We do not limit to stand-alone climate plans but also to adaptation measures mainstreamed in other urban policies, when the formers are lacking. We analyse and discuss the results in terms of gaps and opportunities for future local adaptation policies. We finalise by discussing the adequacy of these metrics in the context of adaptation decision-making and for assessing the odds of building climate resilience.