Environment Canada is calling for heavy rain in the region for much of the day Sunday.
The national weather service has a severe weather statement covering London-Middlesex and most of Southwestern Ontario.
The statement says that rain and heavy rain along with thunderstorms is expected for much of the day. Showers and storms will be more widespread in the afternoon with rainfall amounts of 30 to 40 mm are likely locally, with amounts in excess of 50 mm possible for regions that receive several thunderstorms.
This activity is expected to diminish this evening.