The environmental conditions of livestock farming exhibit a wide degree of variability. In this context, we developed the ADEF, an autonomous data logger to better understand the degree of environmental variables that farm animals are exposed. Each ADEF consists of a set of components: microcontroller, memory card, real-time clock module, ambient sensor (DHT22), two thermal sensors (DS18B20), and an external battery. To validate the accuracy of ADEF, two stages were performed: (1) evaluation in a controlled environment; and (2) evaluation in the field. In both validation, uncertainty analyses were performed in order to determine if a bias correction would be necessary. In the controlled environment, the ADEF recorded consistent data associated with low measurement uncertainty. The high and significant coefficient of determination (~ 0.9; p < 0.05) between the ADEF and commercial data logger indicated statistical model quality and confirmed the accuracy of the measured data. In the field, a total of 40,100 measurements were used for subsequent analysis. Furthermore, the hourly variation in the ADEF variables showed the same pattern and a high correlation (~ 0.9) with the data from the nearest meteorological station. In the field, environmental variables measured by the ADEF demonstrated low hourly dispersion associated with low relative standard uncertainty. The performance of the ADEF system was satisfactory both controlled environment and field, demonstrating that the ADEF can be easily applied as a low-cost tool that allows a more efficient approach to measure the environmental variables in the field.