Abstract
    The studied time duration of this investigation is a 46-year period which consists of years 1965-2010; in addition, the stations of Esfahan, Yazd, Semnan, Kerman and Arak provinces have been selected as the representatives of central Iran. At first, data alteration was recognized by Mann-Kendall rank method and then its kind and time was delineated. The purpose of this study is to investigate the minimum temperature alterations' procedure in Central Iran's regions and its probable changes from usual condition through the usage of Mann-Kendall's non-parameter test. The findings achieved by night temperature analysis revealed that at the start time, most of the alterations were abrupt and both procedural and fluctuating. At all stations, night temperature procedure was positive and therefore, it caused the night temperature get warmer during the period. Also, results indicated that the percentage of winter season in comparison with summer and spring with fall alterations were exactly similar to each other; but, the alterations' start time were not the same at these regions' stations; in addition, one-hundred percent of the alterations have been investigated during the first 23 years of the studied period.