Environment Canada has issued a special weather statement for London, Ont., and the nearby region.
Meteorologists say thunderstorms are expected Sunday with possible hail of 1 to 2 cm.
Wind gusts of up to 70 km/h is also possible.
Environment Canada is calling for a high of 23 C on Sunday feeling like 27 C, and a low of 12 C overnight.
Monday is expected to be mainly sunny with a high of 24 C.
The special weather statement also includes Parkhill, Komoka and Strathroy.