Environment Canada has issued warnings of severe thunderstorms in the Hamilton and Guelph regions, and the region of Waterloo.
The weather agency issued warnings around 11 a.m. that it predicted severe storms capable of producing nickel-sized hail and heavy rain.
They say that the storm is producing strong wind gusts moving eastward at 30 km/h, but can reach as high as 90 km/h.
Environment Canada issued a tornado warning earlier Saturday morning for the region of Waterloo, with eyewitnesses in the Town of Ayr, Ont. reporting funnel clouds in the morning.
The agency lifted the tornado warning for the region just before noon.
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The storm is predicted to produce heavy downpours risking flash floods and water to pool on roads.
This follows after Hurricane Ernesto made landfall in Bermuda earlier Saturday morning.
The Canadian Hurricane Centre says the hurricane expects to bring heavy surf to coastal communities in Nova Scotia as the storm moves northeastward.