The design of line of sight (L.O.S.) or satellite links requires annual point rainfall rate statistics for several percentages of time in the locations where the radiocommunication links are planned. Rain rate data within an average year, indeed, allow the estimation of the time percentage during which attenuation due to rain is significant, and consequently the future link margin.To meet ITU Radiocommunication Sector's Recommendations, we propose a probability law model allowing the prediction of the rainfall rate cumulative distribution in temperate and tropical climates.This model, which can be easily used, may serve as a very useful and accurate enough tool for radiocommunication engineers and scientists.