The present research focuses on the changes of Urmia Lake level. For this purpose, two time
scales have been considered. The trend changes of temperature, precipitation rate and quantitative values of climate type for the observational period from 1968 to 2011 (past scale) and from 2011 to 2100 (future scale) have been analyzed. General Circulation Model (GCM) is considered for simulating the values of the future meteorological components, and statistical models have been used for modeling the lake’s level in future decades. One of the most significant results achieved for the future decades is the increase of the lake’s temperature for around 1.5 degrees centigrade till 2100 in comparison with the long-term average of 1961 to 1990. Furthermore, the values extracted from precipitation rate and climate type of the zone also indicate a remarkable decrease of quantitative values in the future decades. Accordingly, the climate type extracted for the year 2100 with numeric value of around 17.75 will be entered a new phase called arid climate for the first time in recent decades. The Lake surface area is diminished from 5650 square kilometers in 1998 to about 2005 square kilometers in 2010. According to the results achieved by statistical models and time series, if this trend continues, the Lake level will be reduced around 3 more meters in 2100.