Canada has a short but intense mosquito season from May through September, with peak activity during the warm months of June through August. The prairie provinces (Manitoba, Saskatchewan, Alberta), the boreal forest zone, and northern wetlands experience very high nuisance mosquito populations in summer. Southern Ontario and British Columbia have the highest disease-relevant risk.
West Nile virus is the primary mosquito-borne disease concern, with seasonal circulation in southern Canada, particularly in the prairies and Ontario. St. Louis encephalitis, western equine encephalitis, and dog heartworm are also present. Overall disease risk is low, though nuisance biting can be extreme in northern and boreal regions.
Culex pipiens and Culex tarsalis are the main West Nile virus vectors. Various Aedes species create intense nuisance biting in the boreal and tundra zones during summer but transmit no significant human diseases in Canada.
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Explore mosquito risk briefings for other destinations in North America.
Disease presence data is sourced from WHO, CDC, ECDC, and OpenDengue. This is not medical advice — consult a travel health professional before your trip.