Soundings. surface pressure, temperature and humidity obtained from a standard observation network were correlated with rain rates given by raingages and radar. The correlations indicate that a single thermodynamic parameter (static potential energy) explains ∼60% of the storm-to-storm variability of the mean and the maximum rain rates. During the evolution of a precipitating system the time variation of rain rate parameters follows closely the variation of the static energy. The entire distribution of rain rates is well stratified by the energy. Abstract Soundings. surface pressure, temperature and humidity obtained from a standard observation network were correlated with rain rates given by raingages and radar. The correlations indicate that a single thermodynamic parameter (static potential energy) explains ∼60% of the storm-to-storm variability of the mean and the maximum rain rates. During the evolution of a precipitating system the time variation of rain rate parameters follows closely the variation of the static energy. The entire distribution of rain rates is well stratified by the energy.