Environment Canada is expecting thunderstorms with heavy downpours for London-Middlesex, Chatham-Kent and Windsor-Essex.
The weather agency issued a special weather statement Sunday afternoon stating showers are expected to start tonight and last into Monday morning. The rainfall, which will move in from the Michigan border, is expected to affect much of southwestern Ontario.
Environment Canada says some areas may see rainfall amounts of 30 mm to 40 mm by Monday morning. 50 mm of rainfall is also quite possible for locations that receive two or three thunderstorms in a row.
Severe thunderstorm warnings may be issued throughout the night.
The special weather statement has since ended.