Abstract A brief review of previous efforts in Florida and elsewhere to cope with the problem of summer air mass showers is followed by a new attempt to apply to the Miami problem empirical methods of determining the combined effect of several often contradictory shower parameters. Employing the hypothesis that criteria differ seasonally, geographically, and diurnally, this study classifies Miami summer soundings into four rainfall producing types for each of the two diurnal periods and presents averaged dry bulb, wet bulb, and dew point temperatures by 50-mb. intervals to 450 mb. for each type. In addition the heights of the 700-mb. surface and of the freezing level, together with corresponding changes by half days up to three days, are recorded by types. From these and related data, inductive reasoning suggests mechanisms for endemic shower types, and parameters are selected for determining precipitation during the 12-hour period following either sounding. Probability curves that represent also quantita...