Boutou AK, Raste Y, Demeyer H, et al. - As part of the EU/IMI PROactive project, a prospective, multicenter, cohort study was conducted in 236 COPD patients to determine the influence of time and climate conditions (temperature, day length and rainfall) on progression of physical activity (PA). Participants were simultaneously wearing two activity monitors (Dynaport MiniMod and Actigraph GT3X). Over three time points (baseline, 6 and 12 months), the influence of the explanatory variables on PA measures was assessed via a multivariable generalized linear model analysis. Over 1 year follow-up, a significant reduction in PA was displayed by COPD patients, which was further influenced by hours of rainfall, but not by other climate considerations. The only climate factor that had a negative impact on most PA parameters was rainfall.