Rapid urbanization and increasing heat exposure from climate change in combination with the urban heat island effect has become a contemporary pervasive threat to human health. We monitored four urban typologies with temperature and humidity sensors during the 2015 summer peak in Cairo, Egypt to evaluate which typologies could potentially reduce adverse impacts on human health. Our mixed methods approach included qualitative surveys to gauge how people perceived heat stress.  While our monitoring revealed that indoor temperatures were cooler by 1.64°C in the low-density typology relative to outdoor temperatures, the minor indoor temperature differences revealed that building envelopes had little impact on protecting inhabitants.  The study points to the urgent need for more comprehensive empirical monitoring of indoor heat stress in urban areas. Future research would benefit from greater interdisciplinarity so that a more inclusive range of heat stress scenarios, particularly in urban areas in the Global South, can be anticipated, and thereby monitored, mitigated and potentially avoided in order to reduce human health insecurity impacts from climate change.