Urban climate
Temperature & humidity city climate
Urban climate describes the typical climatic features of built-up areas. Buildings, paved surfaces, green spaces and human waste heat alter temperature, wind and radiation.
Why the city has warmth left over in the evening
Roads, roofs and walls store energy during the day and release it later. Paved surfaces also often lack cooling by evaporation. Especially on clear, calm nights, the city can stay warmer than its surroundings. This difference is the urban heat island.
What green spaces change
Trees provide shade, while plants and moist soil cool through evaporation. Their effect depends on vegetation, water availability, buildings and air exchange. An unshaded paved square can have different conditions from a green space.
A city has more than one temperature
Wind, shade, radiation and waste heat vary over short distances. The size of the differences depends on weather and time of day. Urban climate describes these recurring patterns; one hot afternoon alone is not a climate statistic.
In Cologne
Cologne’s urban-climate work examines heat in built-up neighbourhoods, green space and air exchange. In the old town between the cathedral, Great St. Martin and the Rhine, buildings and proximity to the open waterfront are relevant local features. Actual conditions change with wind, cloud cover and time of day; an urban-climate map does not replace a current forecast.