Urban Heat Island (UHI)

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, a phenomenon often known as the Urban Heat Island (UHI) effect. This 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.

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.

Find out more

• BBC weather centre