© CBC NewsThousands of homes are affected by flooding south of Montreal.
Emergency officials in Quebec are closely watching water levels in the Champlain Lake and Richelieu River.

Several towns and villages in the Montérégie region have experienced flooding, evacuations and damages in recent weeks.

The weather forecast calls for heavy rain overnight, leaving emergency officials worried.

"We have 2,000 houses flooded right now, and we have more than 300 people evacuated, mostly in Henryville, St-Jean-sur-Richelieu and Ste-Anne-de-Sabrevois," said Yvan Leroux, head of emergency preparedness for the region.

The Richelieu River could rise another 20 centimetres by Wednesday morning, he warned.

Evacuations are voluntary, and about half of residents in the area have refused to leave their homes.