Water can be employed to address immediate hot spots and provide a much needed "cool break" during heat waves.
What you need to know:
See how others do it:
Fig. 1: Water mist providing a cooling spot during summer heat
The City of Vienna installs mist station and drinking fountains called "Brunnhilde" throughout the whole city in summer. This helps residents to cool down and get some refreshment. Depending on the air humidity in the Nordic cities this might be an inspirational example.