A new study just published looked at the way Urban Heat Island effect interacts with heatwaves. It is not a simple addition of the heatwave increase in temperature added to the urban heat island temperature: heatwaves exacerbate and amplify the Urban Heat Island Effect so that the impact is magnified. This is a major energy use and health concern for people living in cities, particularly the poor and vulnerable.
"Not only do heat waves increase the ambient temperatures, but they also intensify the difference between urban and rural temperatures. As a result, the added heat stress in cities will be even higher than the sum of the background urban heat island effect and the heat wave effect." say the researchers, Dan Li and Elie Bou-Zeid, both from the Department of Civil and Environmental Engineering, Princeton University