Environment Canada is warning of a wet Wednesday followed by extreme heat for the Canada Day long weekend.

Showers and thunderstorms are forecast to affect Southwestern Ontario overnight and Wednesday. The heaviest storms are expected very early Wednesday morning through midday. Total local rainfall amounts could be in the 30 to 50 mm range, with higher amounts possible under the heaviest storms.

Then, beginning Thursday and continuing through the Canada Day long weekend, expected daytime highs are in the low to mid 30°C with humidex values into the mid-40’s °C. Overnight low temperatures will only fall to the mid 20°C, providing little or no relief from the heat.

There is still uncertainty regarding when the heat event will come to an end, and Environment Canada says that current indications suggest the heat could persist into the middle of next week.