Akodon spegazzinii is found in northwestern Argentina, in the provinces of Salta, Catamarca, Tucumán, La Rioja, and Mendoza, at altitudes of . Although its main distribution is in the northern provinces of Salta, Tucumán, and Catamarca, there are also scattered records from the more southern provinces of La Rioja and Mendoza, where it is likely restricted to patches of wet habitat. "Akodon alterus" has been reported from Jujuy, but this record was likely based on misidentified specimens of "A. boliviensis", and records of "Akodon spegazzinii" from Jujuy were based on misidentified "A. sylvanus". "Akodon spegazzinii" is known from a paleontological site in
Climatic regions of Argentina temperate and arid with large thermal amplitudes, long summers, and a long frost free period which varies by altitude. In both the Quebrada de Humahuaca and Calchaquí valleys, winters are cold with frosts that can occur between March and September. In the valleys in the south in La Rioja and Catamarca Provinces, along with the southwest parts of Santiago del Estero Province, temperatures during the summer are very high averaging in January, while winters are mild averaging . Temperatures can exceed during the summer, particularly in the central valley of Catamarca (Valle Central de Catamarca) and the valley of La