Rain, at times heavy, will hit southwestern Ontario Sunday evening and quickly spread to all other regions overnight, Environment Canada forecasts. Expect rainfall of 15 to 30 millimetres before it tapers into showers on Monday.
The rainfall may affect snow melt around Lake Huron and Georgian Bay, which received significant snowfall in the past week. Some localized flooding is also possible in these areas.
The weather system will also bring strong winds — 50 gusting to 70 or 80 km/h — to the region. Localized gusts of 90 km/h are also possible in some areas.
"Winds of this magnitude may bring down some limbs or the odd tree, and cause sporadic power outages," the special weather statement said.
The forecast weather conditions are due to a "rapidly intensifying disturbance" in Kansas that's heading to Ontario, according to Environment Canada. It will track toward Lake Michigan Sunday night and cross northeastern Ontario on Monday.
The same weather system also prompted the agency to issue a special weather statement for much of northern Ontario. Residents there are expected to experience significant weather, such as rainfall, freezing rain and snow, depending on where they live.