Environment Canada warned that a period of extremely cold wind chills is expected for parts of Huron and Perth counties.
"Risks are greater for young children, older adults, people with chronic illnesses, people working or exercising outdoors, and those without proper shelter," the weather agency said.
Dressing in warm, wind-resistant layers is recommended to battle the cold.
Anyone who needs to be outside during this time is advised to watch for cold-related symptoms including:
• shortness of breath
• chest pain
• muscle pain and weakness
• numbness and colour change in fingers and toes
Wind chill values near minus 30 could last from Sunday evening until Monday morning.