The weather agency issued the tornado watches earlier on Wednesday, with the area of concern initially stretching from Windsor to Muskoka and included a good portion of cottage country, including the northern portion of Wellington County, Bruce Peninsula (Sauble Beach), Blue Mountains, Owen Sound, Goderich, Huron and Perth counties, Barrie and London.
The areas around Innisfil, Orangeville and Shelburne as well as Algonquin were included in the tornado watch.
However, by around 9:40 p.m. on Wednesday, tornado watches only remained in Algonquin and Parry Sound – Muskoka.
The tornado watches were issued on top of the special weather statement Environment Canada released earlier in the day warning of severe thunderstorms.
The agency had said the inclement weather would begin to form over eastern Michigan on Wednesday afternoon before heading eastward across Lake Huron toward the affected areas.
It said the area were to see tornadoes, it would likely be late in the afternoon.
Environment Canada urged the public to find cover immediately if threatening weather approached.
The agency said if there is a tornado or a warning is issued for your area, go inside to the room with the lowest floor, like a closet or basement or stairwell, which is not close to windows.
The agency also says those who are in mobile homes, vehicles, tents, trailers and other temporary or free-standing shelters should move to a stronger building if possible.
“As a last resort, lie in a low spot and protect your head from flying debris,” the warning says.
Environment Canada said the threat of severe weather is expected to decline as the storms travel east on Wednesday evening.
As cottage country geared up for the thunderstorms, most of southern Ontario, including a good portion of the affected area, remained under a heat warning Wednesday.
Temperatures were expected to reach as high as 31 C in the afternoon, with overnight lows expected to drop to only 20 C.
Heat warnings in many areas remained in place by around 10 p.m. on Wednesday.
The agency said residents should keep an eye out for the effects of heat illness, including swelling, rash, cramps, fainting, heat exhaustion, heat stroke and the worsening of some health conditions.
Environment Canada said people who need to cool off should look for shade, visit a swimming pool, take a shower or bath, or find an air-conditioned spot.
It also said you should never leave people or pets inside a parked vehicle for any amount of time.
Environment Canada said it expects there to be some relief from the sweltering heat on Thursday.
-with files from Global News’ Hannah Jackson