Seasonal variations in mortality in Québec: deaths highest in January and lowest in August
Notice of release
Québec, October 25, 2023. ‒ From 2000 to 2019, mortality was generally highest in January in Québec, with 14% more deaths than the annual average. The lowest number of deaths was typically observed in August (9% below the annual average). The seasonal fluctuations observed vary in size depending on the cause of death, and the age and sex of the deceased.
These results come from the socio-demographic bulletin La saisonnalité des décès au Québec de 2000 à 2019 published today by the Institut de la statistique du Québec.
More deaths from respiratory diseases in winter, more deaths from external causes in summer
For most causes of death, excess mortality is observed in the winter. This is true for respiratory diseases, which have the highest level of excess winter mortality (+83%), particularly due to influenza. They are followed by circulatory diseases (+28%), the second leading cause of death in Québec. In contrast, deaths from external causes—comprising accidental and violent deaths—are characterized by excess summer mortality, as motor vehicle accidents and drownings are more frequent in the summer. Little to no seasonal fluctuations are observed for deaths from tumours, the leading cause of death in Québec.
Excess winter mortality increases with age
Young men aged 10 to 34 are affected by excess summer mortality because they are more likely than women to die from external causes, and deaths from these causes are more frequent in the summer than the winter. Meanwhile, elderly men and women present excess winter mortality, as they are more vulnerable to respiratory and cardiovascular diseases than younger people. This excess mortality increases with age and becomes similar for men and women from the age of 55.
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