Background: When promoting physical activity practice, it is important to consider the plausible environmental determinants that may affect this practice. We aimed to explore the impact of objectively measured Public Open Spaces (POS) on objectively measured and self-reported physical activity and the influence of weather on this association, in a Mediterranean sample of senior adults with overweight or obesity and the metabolic syndrome. Method: Cross-sectional analyses based on 218 PREDIMED-Plus trial participants aged 55-75 years, from Palma de Mallorca (Spain). Indicators of access to POS were assessed in 1·0 km sausage network walkable buffer around each participant’s residence address using geographic information systems. Mean daily minutes of self-reported leisure-time brisk walking, and accelerometer measured moderate-to-vigorous physical activity at least in 10 min bouts were measured. In order investigate the association between access to POS and physical activity, generalized additive models with gaussian link function were used. Results: Better access to POS was no statistically significant associated with self-reported leisure-time brisk walking. Only a positive significant association was observed between distance of healthy routes contained or intersected by buffer and OB-MVPA. This association was only evident on non-rainy days. Conclusions: In this elderly population living in a Mediterranean city, only healthy routes contained or intersected by 1 km sausage network walkable buffer influenced on accelerometer measured MVPA 10 minutes bouts and rainy conditions during the accelerometer wear period did appear to be an important factor related to active ageing.