Southern New Brunswick should expect between 30 and 65 millimetres of rain to fall by Tuesday morning, according to Environment Canada.
The weather agency has issued a rainfall warning for the region with a forecast of heavy and persistent rain.
The rainfall is expected to be accompanied by mild temperatures and will lead to significant melting and run-off in areas with existing snow.
Strong southwesterly winds that could reach 80 kilometres per hour are also expected.
The federal agency is forecasting the possibility of localized flooding in low-lying areas. Visibility could also be reduced as a result of the rainfall, it says.