One of the best-known effects of urbanization on the local climate is urban warming -- this phenomenon is commonly referred to as the urban heat island (UHI). A range of factors vary between rural and urban areas and contribute to the UHI -- for example, the thermal properties of materials, the height and spacing of buildings and air pollution levels. These factors result in more of the sun's energy begin captured, absorbed and stored in urban surfaces compared to rural surfaces during the day and a slower loss of this energy at night, thus resulting in comparatively higher air temperatures. In addition, less evaporation (with the consequent reduction in associated cooling) takes place in the typically drier urban areas. Finally, urban areas also have greater inputs of heat as a result of the high density of energy use in cities. All of this energy (used in buildings and for transport) ultimately ends up as heat. Strategic planning is therefore required that takes account of the above factors, particularly in the context of climate change.