This study aimed to analyze the usability of NOAA’s climate.gov portal for the four target audiences: (1) the climate-interested public; (2) climate science data users (scientists and applications-oriented professionals); (3) science educators (formal and informal), and (4) climate science policy decision-makers. The study built upon the previous literature review and evaluation study conducted by Mooney and Phillips in 2010 and 2012. The study used the Quality of Relationship index developed in the previous study and placed a new emphasis on the experience of individual users from the four audiences in their regular work or home setting. Multiple methods, including an online survey, usability studies, phone interviews and web statistics were used to draw conclusion and recommendations. The evaluation team is experienced with building and evaluating digital platforms for sharing geoscience information, and is very familiar with the climate literacy context and the NOAA mission. We hope that sharing our results and findings with the larger science communication community will help that community consider ways of taking similar approaches to assessing and evaluating their projects, and possibly by using the Quality of Relationship metric, which will facilitate wider synergies and intercomparison of results in our nation’s overall efforts to boost public science literacy.