Meanwhile, cleanup continues across the GTA following flooding and power outages.
The heat warning issued by Environment Canada for a large chunk of Quebec is expected to end by Wednesday evening.
There is a slight chance of showers in the Montreal area in the afternoon with a very light wind. The high is expected to be 27 degrees Celsius with a humidex of 35 C and a UV index of 9, or very high.
In the evening, there is another chance of showers and a low of 19 C overnight, then a relatively cool 24 C on Thursday.
Heat warnings were issued for areas from the Ontario and U.S. borders, north into the Lanaudière and as far east as St-Hyacinthe.
Meanwhile in the GTA
The cleanup continues Wednesday after a storm front moved through the Greater Toronto Area, causing significant flooding and widespread power outages.
An early morning statement from the Toronto and Region Conservation Authority says their flood warnings have been downgraded, but caution is still required around all bodies of water.
The authority says that at the height of the storm, an excess of 100 millimetres of rain was reported to have fallen in certain areas.
All have since reopened after the flood waters dispersed.