A Special Weather Statement has been issued for Niagara with heavy rain in the forecast.
Environment Canada says rain, at times heavy, will continue today, and is expected to come to an end this evening with total rainfall amounts of 25 mm possible.
It says the frozen ground has limited ability to absorb the rainfall.
A provincial flood watch across southern Ontario noted no major flooding was expected but some localized flooding was possible in floodplains, low lying areas and places with poor drainage.
Residents are being asked to keep children and pets away from creeks and river banks.