Hi Fiona
Canada in June is a lovely time and place to be outdoors, as the days are warm and long. It depends where exactly you are going, of course, but the daytime temperatures are likely to be in the low to mid 20s. The evenings are cooler and there's a chance of the odd thunderstorm too, so it's probably worth taking a waterproof jacket.
I'm sure you'll have a great trip - I went to Toronto a few years ago and loved it.
Kind regards,
Olly, your editor