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Urban Heat Island (UHI)

The 'Urban Heat Island' effect is the phenomenon whereby the temperature in urban areas (particularly at night) is higher than in surrounding rural areas.

In detail

Urban climates are different from those of surrounding rural areas. The UHI effect arises partly because of the different terrain characteristics of city and countryside (such as their reflectivity and the friction effect of their surface), partly due to the ability of buildings to absorb heat by day and release it by night, and partly due to the energy dissipated within the city from human activities.

Find out more


UKCP09 provides a commentary about potential future changes in the Urban Heat Island (UHI). An overview is provided in section 5.13 of the Briefing report, with further details in Annex 7 of the UKCP09 Climate change projections report.