Listen: Just because it’s cloudy doesn’t mean you can go without a layer of sunscreen. The UV index in the Montreal area is 8, or very high, on Wednesday.
You can expect the clouds to dissipate by afternoon.
That comes with a high of 25 C and a humidex of 28 C, then relief as the temperature drops nearly 20 degrees to 6 C overnight before shooting up to 17 C on Thursday.