Summer's over: Strong storms, possible flooding bring an end to the hot weather

A storm system tracking into Quebec is expected to end the summery September heat.

Strong thunderstorms are expected to develop Tuesday afternoon as a cold front digs into the warm and humid air mass that has been sitting over parts of the province since the middle of last week.

Environment and Climate Change Canada has issued rainfall warnings for most areas north of the Saint Lawrence River.

Heavy downpours could drop between 50 and 75 millimetres of rain through to Wednesday morning, potentially causing flash floods and pooling water on the roads.

The Ottawa Valley, Lachute-Saint-Jérôme, the Laurentians, Lanaudière and Mauricie are expected to see the heaviest rainfall.

Montreal and the rest of southwestern Quebec should brace for powerful thunderstorms, heavy downpours and strong winds from Tuesday afternoon to overnight.

Once the cold front moves through, conditions are expected to dry out gradually on Wednesday, with temperatures starting to drop.

The overnight low in Montreal is expected to be in the single digits, with daytime highs below average for the end of the week as sunshine returns.

The weather system is expected to end the summery heat Montreal has been experiencing, with daytime highs in the upper 20 degrees Celsius and humidex values in the 30s.