Environment Canada has issued a special weather statement for Waterloo Region, Guelph and southern portions of Wellington County.
The agency is warning of significant rainfall, which is expected to begin Tuesday evening and last right through Wednesday night.
It says the area could see 40 to 60 millimetres of rain by early Thursday morning.
“This rainfall is due to a cold front and a moisture laden low pressure system that will arrive from the American Mid-west,” the Environment Canada statement read.
The agency says rainfall warnings could be issued later Tuesday.