The Essex Region Conservation Authority has issued a flood watch for the area with up to 25 mm (1 in) of rain expected over the next 12 to 24 hrs.
The conservation authority says low lying areas are especially at risk for flooding.
Officials are also warning that the potential for high intensity thunderstorms means there is an increased possibility of flooding and drainage problems, especially in urban areas.
Property owners are being urged to inspect areas of their properties for catch basin locations or other surface water inlets to make sure they aren't blocked by debris.
The flood watch is in effect until Tuesday morning at 9am.
