Thunderstorms, torrential rain likely all day Tuesday: Environment Canada – The London Free Press

Keep the umbrellas and rain boots handy.

Rounds of showers and thunderstorms are closing in on parts of southern Ontario Tuesday, Environment Canada says, developing over Southwestern Ontario early Tuesday morning before reaching the Golden Horseshoe.

London, Sarnia-Lambton, Chatham-Kent-Essex, Middlesex, Oxford and Elgin counties were under a special weather statement Tuesday morning. Huron Perth is also under a severe thunderstorm warning.

The good news? The rainfall will be sporadic with significant time between each shower.

The bad news? Each one will pack a punch.

The air mass moving over Southwestern Ontario is very moist, the national weather agency says, and will cause torrential downpours.

Many areas will get 20 to 40 millimetres of rain by nightfall, Environment Canada says. Spots that get slammed with thunderstorms can expect even more rain.

The agency is not ruling out issuing rainfall or thunderstorm warnings in some places.

The rain might stick around in London on Wednesday. Environment Canada is calling for a 40 per cent chance of showers and a high of 21 C.

Sunny skies will return Thursday and Friday, with a chance of rain Saturday and Sunday.