The proportion of the world's population living in urban areas is constantly increasing. Different urban shapes result different micro-climates. The way cities are planned and build is therefore important for the global energy use. The city of Mosul ( north of Iraq) had witnessed a rapid urbanization during the second half of the last century, adopting the open grid iron system in planning the new residential areas which now exist beside the traditional compact system. This study present result from measurements of Max. air temperature during hot season in (156) points in the traditional paths of the old city (called zuqaqu) and (44) points in the streets of the modern neighborhoods, more over the engineering-physical characteristics of each point had been measured. Using statistical analyzing for determining the impact of each of these characters on the urban micro climate (Max. air temperature).The primary results show that sky view factor has the major impact on air temperature, and that confirm the important role of the urban designers and planners in the urban micro-climate. Key words: urban micro-climate, traditional city, Mosul.