Irrigation of adult stone pine trees growing in a xeric non-native habitat had positive effects not only in stem diameter growth but also in tree response to climatic variability. The aim was improve our understanding of the effect of irrigation on (1) stem diameter changes of stone pine trees in a drought-prone environment in Chile and (2) the sensitivity of the species to weather conditions. Studied daily stem diameter changes in irrigated and non-irrigated 31-year-old stone pine trees during a growing season with below average precipitation in Chile. Short-term diameter changes were recorded using high-resolution dendrometers. The detrended daily stem diameter changes, expressing tree water status, were correlated with weather variability in both irrigated and non-irrigated trees. Irrigation increased stone pine productivity in this xeric environment and reduced the correlations between daily stem diameter variations and local climatic variability.