Southern Ontario appears to be in the path of a storm front that could spawn tornadoes in the southern Great Lakes region Monday afternoon and evening.

The U.S. National Weather Service's storm prediction centre is forecasting a risk of severe thunderstorms Monday afternoon from southern Texas across the lower Mississippi, Tennessee and Ohio valleys, the Midwest and into the southern Great Lakes area.

The main threats will be damaging winds and large hail, with a couple tornadoes possible across the southern Great Lakes, the agency said in an online statement.

According to the National Oceanic and Atmospheric Administration's outlook on its website, nearly 43 million people are in the path of the storm system that's moving northeast from Texas towards Windsor, Ont.

"Southwestern Ontario and parts of south-central Ontario are also at risk of strong thunderstorms this afternoon and this evening," Environment Canada warning preparedness meteorologist Geoff Coulson wrote in an email to CBC. "If the forecasters here feel that some severe storms will form in southern Ontario, then severe thunderstorm watches or warnings may be issued."

Environment Canada issued tornado watches in Windsor-Essex and Sarnia-Lambton just before 2 p.m. Monday.

"Conditions are favourable for the development of severe thunderstorms which may produce tornadoes. Severe thunderstorms are expected to develop late this afternoon and evening ahead of a cold front. Damaging winds to 90 km/h and large hail are possible. There is also the risk of a tornado," Environment Canada said in a statement. "Be prepared for severe weather. Take cover immediately, if threatening weather approaches.

In the event of a tornado, or if a tornado warning is issued for your area, it is recommended you take the following actions:

Go indoors to a room on the lowest floor, away from outside walls and windows, such as a basement, bathroom, stairwell or interior closet.

Leave mobile homes, vehicles, tents, trailers and other temporary or free-standing shelter, and move to a strong building if you can.

As a last resort, lie in a low spot and protect your head from flying debris.