Calgary Pest Weather Calendar: A Month-by-Month Prevention Guide

Monthly calendar

The temperatures are climate normals, not a forecast. The Calgary airport composite joins observations from Calgary International Airport stations for the 1991–2020 normal period. Conditions can differ across the city and around individual buildings.

Mosquitoes: use water and temperature as prevention cues

Health Canada says mosquitoes develop in still or slow-moving water and that the egg-to-adult cycle can take less than 10 days when temperatures are suitable. It lists 22°C to 27°C as an ideal temperature range. Calgary's normal daily maximum reaches 23.5°C in July and 23.1°C in August, while the daily averages remain lower.

Those numbers support a summer reminder to empty small water containers, clean gutters and change water in bird baths or outdoor pet dishes at least twice a week. They do not support a prediction that July will have a particular mosquito count. Rainfall, irrigation, drainage, local shade and short hot periods all matter.

Public Health Agency of Canada surveillance should not be used as a household mosquito index. West Nile virus surveillance tracks human, animal, bird and mosquito evidence for public-health purposes. A reported case count does not measure the number of nuisance mosquitoes in a Calgary yard. In the 2024 national annual report, Alberta reported zero human West Nile virus cases acquired in Canada, but that historical provincial result is neither a guarantee for another year nor a Calgary abundance estimate.

Wasps: inspect early and reduce food access later

Health Canada advises inspecting yards and home surroundings in early summer for activity or paper nests taking shape. It also notes that outdoor food, sweet drinks, strong scents, pet food and open garbage can draw wasps. Later in summer, the practical response is to cover food and avoid walking barefoot where wasps may be active.

Do not approach or strike an active nest. Health Canada recommends professional help for active-nest removal because a group attack can cause serious injury. Seek medical attention for unusual swelling, itching, dizziness or shortness of breath after a sting.

Ants: identify the route before choosing a control

Ants often enter in search of food or water. Health Canada's first-line measures include cleaning food residue, storing attractive foods in sealed containers, placing compost away from the house and sealing cracks. Carpenter ants can damage wood, and sawdust-like material can be a warning sign, but size and colour alone are not enough for a confident identification.

If a pesticide is used, the label must name the pest and treatment location and carry a Pest Control Product registration number. Spraying a visible trail without addressing the nest or food source can fail, and Health Canada cautions against using spray while also relying on bait.

Rodents: exclusion works year-round

Health Canada says mice can enter through dime-sized gaps and rats through quarter-sized holes. Calgary and Alberta's rat-control history does not make every rodent sign a rat. House mice and deer mice are separate concerns, and the animal should be identified before a trap or treatment is chosen.

Repair foundation cracks, screen vents, use weather stripping, store dry food securely and remove water sources. If droppings are found, do not sweep or vacuum them dry. Health Canada advises dampening the material with a bleach-and-water solution before wiping it up, while using gloves and a dust mask.

For help comparing providers, see the Calgary pest-control category and Calgary pest-control company guide. Our methodology explains why the directory does not claim first-hand treatment results.

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