The province said the deaths of two people over the weekend have been linked to hyperthermia, or abnormally high body temperature.
A provincial spokesperson said officials are working with the chief medical examiner to confirm causes of death, and to see if drug use played a role.
The province said hyperthermia is “caused by a failure of the heat-regulating systems of the body to deal with the heat load from a combination of metabolic heat, environmental factors, and clothing requirements.”
On Saturday, the temperature in Winnipeg reached 29.1º C, and on Sunday, it reached 30.5º C but felt hotter with the humidity.
On Monday, much of southern Manitoba was under a heat warning from Environment Canada.
The province reminded people to take measures to protect against extreme heat and noted some medications can increase the risk of heat-related illness.