Individual sensitivity to adverse effects from climate hazards such as extreme heat is an essential component of vulnerability. For psychological wellbeing in particular, affective and cognitive sensitivity to environmental stressors is a key mechanism that shapes the extent to which people are affected. In this study, we aim to quantify this psychological sensitivity to heat and explore the situational contexts in which it becomes especially pronounced. To do so, we collect experience sampling survey data across multiple countries with a mobile app for Android and iOS devices. Based on GPS and time stamps, we then combine this intensive longitudinal data with secondary data such as weather (e.g., temperature, humidity) and geospatial (e.g., land cover) parameters. We operationalize psychological heat sensitivity as the within-person effect of heat exposure on affect and attentional control. To better understand when this sensitivity is heightened, we examine the moderating effect of environmental conditions (e.g., greenness), situational work demands (e.g., level of intellect required), and thermoregulating behaviors (e.g., wearing lighter and looser clothing). We present preliminary results showing how responses to heat fluctuate over time while also accounting for differences between individuals using multilevel models. This study contributes to methodological advancements in the quantification of psychological sensitivity to climate hazards as well as valuable insights into how adaptive capacities become relevant in daily life to prevent the negative consequences of extreme heat. In turn, this knowledge can support policy development towards more heat-resilient urban environments and work schedules, as well as offer guidance on the most effective protective actions.