This data set contains the critical thermal minimum temperatures (CTmin) of individuals of the restricted tropical ectotherm Carlia longipes over an extensive acclimation process (more than 16 weeks) to a cold temperature regime and supplementary material on the lag of body temperature behind air temperature in the experiment used to measure CTmin. It also includes data obtained from the bureau of meteorology (http://www.bom.gov.au/climate/data/ accessed 10.6.2014 on minimum temperatures recorded during the study as well as experimentally collected habitat temperatures of the study species at the coldest time of day throughout the year. The data was collected in Cairns QLD, Australia, as part of a PhD project from 2012 to 2013. Detailed methodologies can be found in the related PhD thesis and publication.