The observations of rainfall registered in different stations of the Meteorological network of The Colombian Coffee Federation, is one of the inputs for studies, research, monitoring and management of the information used to justify the taking of decisions on the resources, production costs and environmental policy. Sometimes there is not complete information, due to situations such as computers are not calibrated, damage in measurement units, not appropriate measurements or deficiencies in the procedure of observation and measurement, among others. In order to have complete rainfall historical series, a method to estimate missing data easy to implement was proposed, based on data series of accumulated rainfall by cycles in periods of time (monthly), taking into account the grouping by years El Nino, La Nina and Neutro, researched and statistically validated.