Montreal hosts 3 festivals in this guide, in Quebec: Igloofest, Osheaga, îleSoniq.
Montreal has 3 festivals in this guide. They run in January and August, and festival-day temperatures range from -8°C (18°F) to 26°C (79°F), with nights down to -16°C (3°F). That range is the reason there is no single "Montreal festival outfit". The answer changes by month and by site.
1 sits below 16°C, where the outer layer effectively is the outfit.
The ground matters as much as the sky. You will find snow and city park, which puts insulated waterproof snow boots at the top of the list for most of these events. None of them have camping on site, so you are travelling in and out each day and the outfit has to survive the journey at both ends.
Stylistically the crowd here leans urban, snow, techno and apres-ski. Igloofest is the largest of them at around 90,000 people, and it sets the tone the smaller ones react to. None of that is a dress code. It is what you will see, which is worth knowing if you would rather blend in or deliberately not.
