Environment Canada has issued a special weather statement for much of southwestern Ontario, including the Middlesex-London and Elgin County regions.
The weather agency says localized heavy rainfall with near 50 mm is possible Saturday.
Showers and thunderstorms are expected to develop and rainfall warnings may be issued as thunderstorms develop.
Heavy rainfall in combination with other weather factors, such as hail, wind and lightning will make outdoor activities unsafe
Saturday will be mainly cloudy in London, with a 60 per cent chance of showers and a risk of thunderstorms in the afternoon and a high of 26 degrees, feeling more like 32.
Saturday night will remain partly cloudy with showers expected overnight. There is a risk of a thunderstorm with a low of 16 degrees.
