Officials warn severe weather could cause significant damage or destruction to infrastructure, homes and the natural environment.
A tornado watch has been issued as conditions become favourable for severe thunderstorms capable of producing tornadoes over the next several hours.
Forecasters say a severe thunderstorm moving across Lake Huron is expected to reach the Lake Huron shoreline within the next hour.
Conditions across the region could allow the storm to produce a tornado, along with strong and potentially damaging wind gusts exceeding 110 kilometres per hour.
Quarter- to loonie-sized hail and torrential downpours are also possible.
Officials warn severe weather could cause significant damage or destruction to infrastructure, homes and the natural environment.
Residents are being urged to be prepared to take shelter immediately if threatening weather approaches.
If a tornado develops or a tornado warning is issued, people should move indoors to the lowest level of a sturdy building and stay away from outside walls and windows. Basements, bathrooms, stairwells and interior closets can provide shelter.
People in mobile homes, vehicles, tents, trailers or other temporary structures should move to a sturdy building if possible.
Anyone on the water should head to shore and seek shelter immediately if threatening weather approaches.
Warning signs of a possible tornado can include a roaring sound, funnel cloud, swirling debris near the ground or flying debris.
Emergency Management Ontario recommends taking cover immediately when threatening weather approaches.
