In the Report “Seasonal and daily climate variation have opposite effects on species elevational range size,” Chan et al. have added a supplementary addendum. This document aims to (i) describe additional technical details of the study, (ii) reproduce in detail the key results, and (iii) make the analytical approaches used in the Report accessible and applicable for other research purposes. In addition, it corrects three typographical errors and one data error in the original supplementary table S2. These corrections do not change the findings or conclusions of the study.