Urban expansion, pollution growth, and development of major industrial activities in metropolitan areas impacted local climates of major towns. Transforming big cities into heat islands is one of the most important results of micro-climate change. In this study, variation of some of the important climate factors (such as precipitation, temperature, relative humidity, and percentage of cloudiness) was reviewed in order to study micro-climate changes. The city of Mashhad selected for this study, as metropolitan area. The study performed by comparing the climate parameters of this city with the neighboring regions, which placed at the same climate categories. According to the effective role of rainfall in the urban weather modification and decreasing of pollutions, rainfall variation will be more important and sensitive. The result of this research shows that rainfall variation follows the change of temperature trend. A significant correlation between temperature and precipitation changes showed the effect of heat island on urban climate parameters. The urban heat island phenomenon increases the hot season rainfalls when we have decreasing effects on cold season.

Keywords