Abstract Indoor temperatures during winter conditions play an important role in influencing the comfort and health of households, space heating energy demand and peak heating power. The role that physical dwelling features and household characteristics have on wintertime indoor temperatures has been examined among low-income households, but not across English households in a systematic manner. This paper examines determinants of indoor air temperatures during wintertime conditions to examine how temperature conditions vary with, for example, dwelling age or household socio-economic conditions. Using a cross-sectional survey of English dwellings that included monitoring of indoor air temperatures from January 2011 to February 2012, this study examines the determinants of indoor temperatures during wintertime conditions within a representative sample of English dwellings (N = 821). The study analysed indoor temperatures standardised to outdoor air temperatures of 0 °C, 5 °C and 10 °C within the study sample and the influence of physical dwelling features (type, age, size), household characteristics (tenure, income, composition, benefit receipt) and energy performance (loft and wall insulation, heating system and performance rating levels). The analysis finds that as dwelling age decreased (i.e. newer), so did indoor air temperatures in both the living room and bedrooms, after adjusting for a selection of dwelling and household characteristics. Compared to the lowest income quintile, households with higher incomes kept warmer temperatures, but this was not a linear increase and the highest incomes were not on average the warmest. There appears, however, to be little change in the dwelling temperature trends when looking at lower or higher outdoor air temperature conditions (i.e. 0 °C and 10 °C). In designing policies to improve indoor thermal conditions, policymakers will need to consider underlying energy performance of the dwelling alongside the socio-economic conditions of the household, for example when providing fuel support payments to at risk households.