The humidex could reach the high 30s to low 40s by Sunday, Environment Canada reports.

Maximum afternoon temperatures near 30 C are expected with humidex values in the high 30s this week for central Ontario.

Winds gusting up to 50 km/h in many parts of the province and thundershowers are in the forecast for both Saskatoon and Regina.

30-degree humidex values across the province and thundershowers are in the weather forecast for Saskatoon and Regina.

The heat will continue throughout the weekend, reaching a possible high of 34 C Saturday for Winnipeg - and that's before the humidity is factored in.

There will be little relief from the heat overnight, with lows of 20 degrees expected.

The heat warnings have been issued for all of Tuesday and into Wednesday, with temperatures are expected to decrease into the evening.

Environment Canada says a relatively hot and humid air mass has reached the area and will remain in place through Friday.

The heat alert calls for a high of 32 C on Friday, which will feel closer to 38 C with the humidex.

The hot and humid conditions will continue Wednesday as the forecast calls for a mix of sun and cloud and a high of 26 degrees.