Sarnia-Lambton is under its first "Cold Weather Alert" of the winter.
The Medical Officer of Health issues an alert when the low temperature is forecast to drop to -15 C or 5 F.
Lambton Public Health's Paul Buttery says overexposure can lead to frost bite and hypothermia.
"Plan ahead, limit your time outdoors, stay out of the wind, dress warmly," says Buttery. "You want to dress in layers and make sure your outer layer is wind resistant. Seek shelter, so stay inside when it's this cold."
During an alert, public health advises local agencies that provide shelter and assistance to the homeless to prepare for an increase in demand.
The alert is expected to be in effect for Monday night only.
