It has been shown that meteorological conditions and season affect physical activity (PA) during adolescence. Today, meteorological conditions have never been combined to study their influence on PA level in a single sample of a large adolescent multicountries population. The aim of this study was to explore the influence of meteorological conditions on PA in adolescents from several European countries. The study included 2024 healthy adolescents aged 12.5-17.4 years who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional study. Participants wore a uniaxial accelerometer for 7 consecutive days to measure total PA and moderate to vigorous physical activity (MVPA) in a one-off measurement manner. Comparison of PA according to meteorological conditions was done using linear mixed models. The highest difference of MVPA was observed in boys on free days when comparing the best meteorological conditions versus the worse (ie, +39% with highest temperature, +29% without rainfall, +39% with highest sunlight duration and +21% with highest length of day) and in girls on free days (ie, +26% with highest sunlight duration). This increase in MVPA contributed to a simultaneous increase in total PA when considering the same meteorological condition parameters. Meteorological conditions act as a determinant of PA differentially between boys and girls. PA and MVPA in boys are mainly modified by meteorological conditions on free days whereas PA and MVPA in girls are modified by sunlight duration.