A facility for controlling the grain moisture provided with a grain storage silo (1)conveniently installed on a hard flat floor (9) and inside of which an elevated floor (10) comprising air passageways is provided, determining an air chamber (18) inside the silo (1) and below the perforated floor (10), into which previously conditioned air is blown by an air heater, wherein the control of hot air blowing times is determined based on means of modeling and calculating on and off times applied through an electronic control means, with the ability to read and record manual input data entered by an operator and reading data from a temperature sensor in the air chamber (18), below the perforated floor (10), further aided with an ambient temperature and moisture sensor, thereby causing the application of different stages of drying, re-humidification and maintenance of the grain moisture.