Environment Canada meteorologists are tracking a line of severe thunderstorms capable of producing very strong wind gusts, up to nickel size hail and heavy rain.
Affected areas include St.Catharines, Welland, Northern/Southern Niagara Region, Niagara Falls, Hamilton, Grimsby, Burlington, Oakville, Dunnville, Caledonia, and Haldimand.
Heavy downpours can cause flash floods and water pooling on roads.
Large hail can damage property and cause injury.
Strong wind gusts can toss loose objects, damage weak buildings, break branches off trees and overturn large vehicles.
Remember, severe thunderstorms can produce tornadoes.
Lightning kills and injures Canadians every year. Remember, 'when thunder roars, go indoors!'