Presented is the review of the indices of weather condition comfort that are most frequently used in biometeorology. Described are practical and laboratory experiments carried out by the authors that helped deriving formulae for their computation as well as the limits of applicability of these indices. To assess the impact of changing weather conditions and their aggregate (biometeorological indices) on population health in different seasons, the data of medical statistics were used: on daily mortality of heart attacks in Murmansk (2001-2004), on daily mortality of coronary heart disease in Moscow (2007-2010), and on daily ambulance calls with the essential hypertension diagnosis in Kislovodsk (2006-2008). Determined are the indices having significant correlation with the data of medical statistics. Using the method of cross-correlation analysis of the daily series of ambulance calls and deaths, it was possible to identify the period of the response of the human organism with cardiovascular diseases to changing weather conditions during the warm and cold seasons.