Extreme weather and heat waves play a significant role in affecting people’s health. These events are expected to increase in the future even in regions where heat waves are not common. The terms “extremely hot weather“ and “heat wave“ are defined in the Estonian context. Epidemiological studies have revealed relationships between ambient air temperature and the risk of death for a population. Few of these deaths arise as a direct effect of heat (hyperthermia); they are rather due to the effects of temperature on chronic diseases, particularly cardiovascular and respiratory diseases. The effect of heat waves has great geographical heterogeneity. In Estonia, mortality during the heat wave episodes in 2010 increased by 30% in comparison with expected seasonal mortality. The impact on mortality increases with age. Elderly persons in urban dwellings without Access to an air-conditioned environment are the most vulnerable subgroup of adverse heat effects. A shift in the knowledge, attitudes and behaviour as well as improvement in housing and man-made outdoor environment could help adapt to climate change and reduce adverse health outcomes.