The temperature will very likely be warm, 20s to 30s ºC, but it can get cold at night, especially near the St-Laurent River. Also, there's the occasional cold day. I remember freezing my ass off on a ride last year, it rained all day and the temperature was around 14ºC, around mid-july if I remember correctly.

As for rain, if you're lucky, you won't get any. If you aren't, you'll get some. Realistically, you're likely to see a few showers if you spend a week, but you can expect mainly sunny skies. Also, be careful with historic temperature averages, because the temperature in Quebec can vary a lot from year to year - and day to day for that matter.

Basically, bring a raincoat and a warm swater, and some pants that can unzip to shorts and you'll be fine!

And bring some mosquito repellent. You might encounter some, especially north of the St-Lawrence.