Sorry, Les, the link says "airport" at the top.
You are right, Slobodan, the link says Toronto Airport, I didn't notice that. I suspect that the airport is the (only) official spot for measuring the Toronto temperatures. As to the assumption that the airport has more concrete than other parts of the city that wouldn't hold truth, there is a lot of concrete (both in the horizontal and vertical directions) also in other parts of the city. Interestingly, nobody before raised this point.
Lake Ontario provides some cooling effect to the southern portion of the city close to the lake, but I bet most of Toronto experienced today the same high temperatures as the airport. The airport is in the northwest end. For the uninitiated, there is a city of Toronto and the so called Greater Toronto area (GTA), the most populous metropolitan area in Canada. It consists of the central city of Toronto and the four regional municipalities surrounding it. I live in the northern end of GTA, about 20 miles north of Lake Ontario and 30 miles from the airport. Next time, we'll get such a hot day, I'll measure the temperature in my backyard and compare it with the airport readings. That's if I won't head up to some lake up north.
BTW, I had problems posting my reply, kept getting error messages that the Luminous website couldn't be reached - possibly because the temperature was too hot.