Wearing the right clothes when snowmobiling is the most important factor to ensure a comfortable ride. Here is what we recommend on a very cold day :

Base Layer: Wear synthetic thermals that are tight fitting for your top and bottom pieces.
Mid Layer: Fleece is a comfortable midlayer to wear. We recommend fleece pajama bottoms paired with a hoodie.
Outer Layer: Snow pants and a PUFF jacket (down or synthetic) are the warmest
Socks & Boots: Your footwear should be waterproof boots or shoes designed to repel water. You can find snow boots or shoes with wool lining inserts if you need that extra bit of insulation to keep your toes nice and warm.
Gloves & Mittens: We recommend bringing both, as well as, hand warmers.
Head Gear: A nice warm cap with a tight weave works well. We recommend a fleece hat.
Goggles: Goggles with multiple lenses for different weather conditions, and replacements. You should protect your eyes against any snow and ice that can kick up.
Balaclava or face mask

In the Mont Tremblant area, snowmobiles are kept primarily as recreational vehicles, for people who enjoy getting out in snowy weather.