In recent years, climate change has been considered one of the leading factors affecting the health of the population, one of the conditions for the implementation of this concept for specific risk factors in St Petersburg is the development and use of adequate methods. In this work, as a methodological basis for assessing the state of health of the population, taking into account climatic conditions, the methodology of MR 2.1.10.0057-12 “The state of health of the population in connection with the state of the environment and living conditions of the population. Assessing the risk and damage from climate change affecting the increase in morbidity and mortality in high-risk population groups. Guidelines” was used. The presence of statistically significant correlations between the effective air temperature in St Petersburg and the primary incidence of diabetes mellitus in people older than working age has been established (Spearman rank correlation coefficient –0.829, p = 0.042); primary incidence of acute respiratory infections of the upper respiratory tract in children 0–14 years old (Spearman rank correlation coefficient –0.886, p = 0.019); primary incidence of chronic obstructive pulmonary disease in children 15–17 years (Spearman rank correlation coefficient –0.943, р = 0.005). The presence of established direct and inverse statistically significant correlations can be explained logically based on modern ideas about the impact of climatic parameters on human health, however, in this case, the logical connection seems doubtful due to the highest deviation of the average annual air temperature from the norm in 2020 and the pandemic of a new coronavirus infection COVID-19. Therefore, a decrease in morbidity (in the case of a negative correlation) can be explained by a reduction in planned medical care.