A severe thunderstorm watch has been called for Niagara.
Environment Canada says conditions are favourable for the development of severe thunderstorms that may be capable of producing strong wind gusts, large hail and heavy rain.
The threat of severe thunderstorms this afternoon and early this evening is associated with a cold front moving across Southern Ontario.
Thunderstorms are also possible well in advance of the front.
Strong wind gusts can toss loose objects, damage weak buildings, break branches off trees and overturn large vehicles.
Heavy downpours can cause flash floods and water pooling on roads.
Officials reminding the public that lightning kills and injures Canadians every year, and to remember, when thunder roars, go indoors.