Evaluation, determination and monitoring of wet and dry periods at time scales of 3, 6, 12, and 24 months, in accordance with location and time, could be done by using the SPI model in Turkey. ###>Evaluation, determination and monitoring of wet and dry periods at time scales of 3, 6, 12, and 24 months, in accordance with location and time, could be done by using the SPI model in Turkey.