Urban spaces get trapped in a bubble of heat. The high levels of heat emissions get trapped in their environment due to the high levels of carbon dioxide emitted. This is known as the Urban Heat Island effect. This is further worsened by the lack of green spaces in urban areas, which prevent the land from absorbing heat in the day and releasing it at night.
To combat these, we must address the drivers of UHI - heat and carbon emissions. But it is not as simple as just cutting emissions overnight. Cities need to be redesigned to be less dependent on polluting practices like excessive cars and have better public transportation and pedestrian infrastructure. We need better insulation/cooling of houses to reduce heating/cooling related emissions. We need more green spaces and lesser unnatural, concretized surfaces that heat up our cities more.