<P> An urban heat island ( UHI ) is an urban area or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities . The temperature difference usually is larger at night than during the day , and is most apparent when winds are weak . UHI is most noticeable during the summer and winter . The main cause of the urban heat island effect is from the modification of land surfaces . Waste heat generated by energy usage is a secondary contributor . As a population center grows , it tends to expand its area and increase its average temperature . The less - used term heat island refers to any area , populated or not , which is consistently hotter than the surrounding area . </P>
urbanization is the cause of urban heat island a condition that could be described as
an urban area or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities