Why is windsor warmer than toronto?

The main reason is the location. Windsor is much more south than Toronto. It is actually on the same line as northern California. So it gets more direct sun and warmth.

Also, the Great Lakes have a different effect. Toronto is next to Lake Ontario. It is a very deep and cold lake. This lake acts like a big air conditioner in the summer, making Toronto cooler.

Windsor is between Lake Erie and Lake St. Clair. These lakes are very shallow. They warm up much faster in the summer. Windsor also gets a lot of warm, humid air that comes up from the United States. This makes its summers feel much hotter.

So, it is more south and it is not cooled by a big deep lake. That is why it is one of Canada's warmest cities.