Tens of thousands of people across Ontario and Quebec are without power after severe thunderstorms on Canada Day brought down trees and flooded homes in some regions during a stubborn heat wave that is now spreading further east.

Environment Canada has scores of heat warnings posted for most of Ontario and Quebec, and now stretching across to New Brunswick, Nova Scotia and Prince Edward Island.

Much of Ontario is under an orange warning, an alert the agency says is uncommon and signals severe weather that is likely to cause significant damage or health effects.

Daytime temperatures in Ontario — from Windsor to Ottawa and Thunder Bay through Timmins and southern James Bay — have been in the mid-30s, with the humidex making it feel even hotter.

Similar heat warnings across much of Quebec, including Montreal and Quebec City, are forecasting highs around 33 C and humidex values near 45 C.

And in the Maritimes, Environment Canada says those in New Brunswick, P.E.I. and mainland Nova Scotia can also expect to feel the heat that is expected to linger into the weekend.

Severe thunderstorms and high winds on Wednesday caused widespread outages in Ontario and Quebec, including in the National Capital Region where several Canada Day celebrations, including the planned fireworks show, were cancelled.

As of Wednesday, Environment Canada said roughly 110 millimetres of rain had fallen at the Ottawa Airport.

At one point, Hydro One in Ontario was reporting 168,000 customers in the dark. The utility said on social media that while crews were making significant progress restoring power, some customers in the hardest-hit areas could be without power heading into Thursday.

Tens of thousands of customers were still without electricity as of late Thursday morning, according to Hydro One’s outage map. The utility said in a post on social media that it is responding “safely and quickly,” urging people to keep drones grounded to allow a clear airspace for helicopters.

More than 9,000 Quebec addresses were also without power late Thursday morning, according to Hydro-Quebec.

The severe heat also comes as Toronto hosts its sixth and final match of the FIFA World Cup.

The city says in a notice that Thursday’s match broadcasts at Nathan Phillips Square, Toronto’s City Hall, have been cancelled due to an extreme heat forecast.

Portugal is set to face off against Croatia in a Round of 32 match to be held at Toronto Stadium.

This report by The Canadian Press was first published July 2, 2026.