Prince County P.E.I., most of New Brunswick, as well Digby and Yarmouth counties in Nova Scotia could receive up to 50 millimetres of rain after midnight and into Thursday afternoon.
The low-pressure system moving north from Maine is expected to stall over the Maritimes, bringing between 30 and 50 millimetres of rain.
Flooding is of particular concern, especially for parts of New Brunswick where ice jams threaten to block river systems throughout the province.
Ground still frozen after this year’s long winter reduces the soil’s ability to absorb water, further increasing the risk of flooding.
Environment Canada warns the heavy downpours can cause flash floods and water to pool on roads.
Road conditions could deteriorate on Thursday if the rain changes to periods of snow and ice pellets on P.E.I. and in parts of New Brunswick.
Southwestern Nova Scotia is expected to receive the heaviest rainfall. There’s also a Les Suêtes wind warning in effect for Inverness County with gusts of up to 110 kilometres an hour.
Northeastern New Brunswick, including the Acadian Penninsula, is also under a freezing rain warning.
Tips to prepare for flooding- Clear all culverts, catch basins and watercourses to ensure water can flow freely. Ensure there’s no snow, trees, garbage or other debris blocking them.
- Clear fire hydrants around your house.
- If your home has a backwater valve installed on the sewer, follow the manufacturer's instructions for cleaning to ensure it's functioning properly. Check that your sump pump is working as well.
- If your home is prone to flooding, get valuable items off the basement floor.
- Clean your eavestroughs. When they're blocked, rain will pour over the edges and could spill into your basement.
- Stay away from fast-flowing streams and ponds, and stay off the ice.
- If you see a flooded area, don’t go near it. Don’t try to drive your car or walk through it.
- Stay away from areas known to flood.