In recent years, summers and heatwaves in France have drawn increased attention due to the escalating impacts of climate change, particularly concerning potential health impacts on the most vulnerable population. While 25% of the French households have adopted air-conditioning systems in recent years, most of households remain unequipped and are especially not adapted to such warm indoor temperatures. This challenge is especially pronounced in southern regions and in urban areas experiencing significant urban heat island effects at night. This study presents an analysis of data collected from an experimental campaign conducted in 76 French dwellings during the summer of 2023. The dataset includes outdoor and indoor temperature and humidity measurements, alongside subjective thermal comfort assessments obtained via a “comfort box” where occupants reported their thermal comfort levels. Additional data were collected on building characteristics, window opening behaviors, utilization of solar shading devices, and the use of electrical fans. The objective of the analysis is to provide an understanding about the current state of thermal discomfort in dwellings during summer. This includes analyzing the thermal tolerance to heat of building occupants, and occupant behavior during summer period and heatwaves.