Weather warnings: potential heavy thunderstorms, extreme heat on Canada Day

Environment Canada is warning of potential heavy thunderstorms for the rest of Wednesday, and also a very hot Canada Day.

The agency says the heaviest storms are expected through midday, followed by temperatures as high as the mid thirties late this week.

Total local rainfall amounts could be in the 30 to 50 millimetres range, with higher amounts possible under the heaviest storms, says Environment Canada.

A persistent southwest flow is then forecast to develop, bringing hot and humid air from the Gulf of Mexico according to the agency.

Environment Canada is also forecasting a hot Canada Day. 

They say beginning Friday or Saturday and continuing through the Canada Day long weekend, expected daytime highs are in the low to mid thirties with humidex values into the mid forties.  

The agency saying this will likely be the most significant heat event of the season thus far. 

Overnight low temperatures will only fall to the low twenties, providing little or no relief from the heat, says the agency. 

There's still uncertainty about when the heat event will come to an end, according to Environment Canada. They say current indications suggest the heat could persist into the middle of next week.

The agency says heat warnings will be issued closer to the weekend.