Global temperature is rising and heatwaves occur with an increased frequency, intensity and duration. Moreover, the urban heat island effect amplifies this heat in cities. How people experience heat is not only dependent on temperature, but also on wind, radiation and humidity. Heat stress is when people experience adverse effects due to heat. Heat and heat stress have adverse effects on economic, sociological and health sectors and are therefore worthwhile investigating. This is especially the case in African cities for different reasons. (1) They will be confronted with the most devastating heatwaves resulting from climate change, (2) near to nothing is locally known to prepare for the impacts of extreme heat, (3) the cities are projected to grow very fast and (4) many people live in steel-roofed houses which get very hot. This PhD will deal with this heat stress, especially in African cities, on a very high resolution by using climate projections and innovative methods to calculate heat stress indicators at meter-scale level.