Anyone here familiar with Ontario weather?

That’s Ontario, Canada.

I’ll be traveling to Toronto in July and want to do some bike touring nearby (probably the Greater Niagara Circle Route.) But I understand the weather can be very hot and humid. What I am wondering is, with the long days, are the evenings noticeably cooler? If so, what time does it start to cool down? Is there much cloud cover in the mornings, or does it heat up fast? I don’t do well with heat, so I want to try and plan my trip to avoid as much of it as possible :>)