The heat goes on in southern Ontario and southern Quebec Thursday, with humidex values in the high 30s and low 40s.
CBC meteorologist Jay Scotland said temperatures should be slightly less warm than Wednesday, but still hot and humid.
Ottawa officially reached heat wave status yesterday — three straight days of 32 C or higher — and Toronto could follow suit today after a high of 34.8 C on Wednesday. The temperature was already 27 C in Toronto's downtown as of 7 a.m. ET.
"That would be seasonal average for a daytime high, and we're nowhere near the daytime high just yet," Scotland said.
Montreal should see highs below 30 C, but it will still feel in the high 30s with the humidex, Scotland said. There is a high heat and humidity warning in place for parts of southern Quebec, including Montreal.
The humidity fuelled strong thunderstorms from eastern Ontario to New Brunswick yesterday, leaving as many as 60,000 customers without power in Montreal. About 8,100 Hydro-Quebec customers were still without power as of 7 a.m.
With a cold front approaching, the same possibility for storms exists today, especially for Ontario, Scotland said.
Quebec health officials said on Wednesday that they are investigating two deaths that may be connected to the heat.
Officials urged anyone caught in the heat to drink lots of water and, if possible, seek relief in a local cooling centre, or an air-conditioned spot such as a movie theatre.
Scotland said the heat will break by the weekend.
Hot weather has also affected the U.S. this week, with the country's largest heat wave of the summer stagnating over large regions, bringing sizzling temperatures from South Dakota to Massachusetts.
People take in the sun at Sugar Beach in Toronto on Wednesday, July 4, 2012.
A woman and her dog cool off in a pond in Montreal on Wednesday, June 20, 2012. THE CANADIAN PRESS/Paul Chiasson
Indian youths play in the River Ganges as they try to beat the heat in Allahabad, India, Thursday, June 21, 2012. Northern India has been experiencing severe hot weather with maximum temperatures touching around 45 degrees Celsius in some areas. (AP Photo/Rajesh Kumar Singh)
People cool down in the water sprinklers at Dundas Square as they take in the extreme heat in Toronto on Tuesday, June 19, 2012. Environment Canada has issues a heat alert for the next few day in Southern Ontario and Toronto. THE CANADIAN PRESS/Nathan Denette
Four-year-old Solaris Arias, of Providence, R.I., right, jumps through water spraying from an open fire hydrant in Providence, Wednesday, June 20, 2012. Much of the state remained under a heat advisory Tuesday afternoon because of the steamy air mass that has moved into the region resulting in temperatures in the 90s (F). (AP Photo/Steven Senne)
A woman cools down in the water sprinklers at Dundas Square in Toronto on Tuesday, June 19, 2012. Environment Canada has issues a heat alert for the next few day in Southern Ontario and Toronto. (AP Photo/The Canadian Press, Nathan Denette)
Michaela Blankenship, age 9, jumps into a pool in her family's front yard as she tries to beat a summer solstice heat wave in Baltimore, Wednesday, June 20, 2012. Also pictured are neighbors Dylan Vaden, from left, Devin Vaden and Jon Morris. (AP Photo/Patrick Semansky)
An Indian youth swims in the Dhansari river as she cools off during a hot summer day in Dimapur, India's northeastern state of Nagaland, on May 19, 2012. Many parts of India are experiencing a heat wave as temperatures rise with the onset of summer. STRDEL/AFP/GettyImages
A Bengal tiger is hosed by a spray of water from a zookeeper on a hot summer day at the Birsa Munda Zoological Park in Ranchi on May 30, 2012. Zoo authorities are helping the animals cope with temperatures in excess of 40 degrees Celsius by providing coolers, special roofs and regular hose-downs. STRDEL/AFP/GettyImages
An Indian boy bathes under a water pipe in a canal to cool off on a hot day in Allahabad on May 17, 2012. Temperatures soared in Allahabad to a maximum temperature of 45.5 Celsius (114 Fahrenheit). STRDEL/AFP/GettyImages
An elephant sprays water on itself on a hot summer day in Allahabad, India, Monday, June 18, 2012. Northern India has been sweltering under extreme heat as maximum temperatures hovered around 45 degrees Celsius (113 degrees Fahrenheit) in some areas. (AP Photo/Rajesh Kumar Singh)
An Indian mahout bathes his elephant on a hot summer day in Allahabad, India, Monday, June 18, 2012. Northern India has been sweltering under extreme heat as maximum temperatures hovered around 45 degrees Celsius (113 degrees Fahrenheit) in some areas. (AP Photo/Rajesh Kumar Singh)
A man submerges himself in water to cool off on the outskirts of Bhubaneswar, India, Saturday, May 26, 2012. (AP Photo/Biswaranjan Rout)
A dog wears sunglasses on a hot spring day in Madrid, on June 6, 2012. DOMINIQUE FAGET/AFP/GettyImages
A squirrel runs past Londoners enjoying the warm weather in Saint James Park in central London on May 29, 2012. MIGUEL MEDINA/AFP/GettyImages
US President Barack Obama dabs perspiration from his brow on a hot day, before placing a wreath at the Vietnam Veterans Memorial for ceremonies to commemorate the Vietnam War's 50th anniversary on Memorial Day May 28, 2012 in Washington, DC. Memorial Day is observed in remembrance for those died while serving in the US military. MANDEL NGAN/AFP/GettyImages
A rhesus macaque eats watermelon, provided by zookeepers to help the monkeys deal with hot summer temperatures, at the Kamla Nehru Zoological Gardens in Ahmedabad on May 18, 2012. The rhesus monkey (macaca mulatta) is native to northern India, Bangladesh, Pakistan, Burma, Thailand, Afghanistan and southern China. AFP PHOTO / Sam PANTHAKY
Pakistani youths cool off in a polluted canal during a hot day in Rawalpindi May 11, 2012. Heat-wave conditions in Pakistan brought a high of 41 degrees celsius in some parts of the country. FAROOQ NAEEM/AFP/GettyImages
Boys cool off in a fountain outside the Donbass Arena stadium, in Donetsk, Ukraine, Thursday, June 14, 2012. Hot weather has set in with temperatures rising up to 31 Celsius (89 Fahrenheit) in Donetsk on the eve of the Euro 2012 soccer championship Group D match between France and Ukraine in Donetsk. (AP Photo/Efrem Lukatsky)
A woman wearing a bikini jumps in the Danube river, in Vienna during a hot sunny day on June 19, 2012. ALEXANDER KLEIN/AFP/GettyImages