Summer in Montreal runs from early June through mid September when temperatures can vary tremendously. Daytime temperatures can reach into the 90's with high humidity, especially in July and August. Lows in the 50's are rare but not unheard of. Budget travelers should make sure rooms are air - conditioned during July and August.
Because there is always a possibility of rainstorms or more likely, summer showers, visitors should be prepared with an umbrella. Comfortable walking sandals and a light jacket for the evenings are recommended. For sight seeing activities, light weight clothing is best. Heavy jeans and hoodies can be very uncomfortable on Montreal's hot, humid days.
Dress in Montreal is best described as fashionable, but understated for both men and women. The emphasis is on clothing of good quality and cut especially for evening and business wear.
The business casual dress code that is so prevalent elsewhere, never really caught on in Montreal. The simple black dress would never be out of place here. Baseball hats and track pants are a no no. Younger people too, dress with an eye to style. Flash, trash and cheap are best avoided when packing for your trip to Montreal.