Weather watch upgraded to a warning for south Niagara, north Niagara still under a watch

thunderstorm bonnie

A severe thunderstorm watch in Niagara has been upgraded to a warning for the southern part of the region.

Environment Canada has issued a severe thunderstorm warning for Niagara Falls, Welland, and other southern areas.

A watch continues for St. Catharines, Lincoln and the rest of the Niagara's north.

Watches are issued when conditions are favourable for the development of severe weather. Warnings are issued when severe weather is either imminent or occurring.

The thunderstorms are expected this evening, and may bring strong wind gusts up to 100 km/h, large hail up to 2 cm in diameter and heavy rainfall of 50 mm within an hour.

Officials say large hail can damage property and cause injury, and strong wind gusts can toss loose objects, damage weak buildings, and break branches off trees.

Heavy downpours can cause flash floods and water pooling on roads.