UK heatwave: Why do our cities get so hot?

City centers during heat waves European Commission Joint Research Center– external.

In extreme cases, the difference may be up to 10C (50F), especially in very calm weather with very little wind to mix the air.

A main reason for this contrast is hard, dark surfaces such as buildings and roads that dominate urban landscapes.

Instead of reflecting the energy of the sun, they absorb, ie they keep heat. This is then slowly released into the surrounding air, especially at night, causing higher temperatures.

Waste heat produced by air conditioning units, vehicles and humans contributes further.