Wind chill is the number that matters, not the temperature

Wind chill expresses how cold the combination of air temperature and wind actually feels on skin, and it is the figure that determines what you need to wear on a given day. Environment and Climate Change Canada includes wind chill in forecasts when the temperature is below zero and the wind is above 5 km/h, and it is the reason a −12°C day with strong wind can be more dangerous than a still −20°C one.

The practical threshold comes from Health Canada, which states that wind chill values below −27 significantly increase frostbite risk and that wind chills can cause the body to lose heat faster and skin to freeze very quickly. For scale, some northern Canadian communities record wind chills below −70. A −20°C air temperature in Toronto with a stiff wind puts the wind chill into the range where uncovered skin is a real concern rather than a discomfort.

How Environment and Climate Change Canada warns you

Cold warnings in Canada are issued relative to local climate rather than against a single national number. Environment and Climate Change Canada issues cold warnings at different temperatures depending on where you live, defining an extreme cold event as temperatures lower than usual for the local climate combined with very low wind chill values and frostbite risk. There is no separate wind chill warning product: wind chill is folded into the cold warning rather than announced on its own.

That regional calibration is exactly why a visitor should not import assumptions from one Canadian city to another. A temperature that triggers a warning in Vancouver is an ordinary January morning in Winnipeg, and the warning is telling you something about local conditions relative to normal, not issuing a universal danger level. Check the forecast for the specific city you are in on the day.

Layering, and what visitors consistently underestimate

Health Canada's clothing advice is short and specific: dress in layers with a wind-resistant outer layer, wear warm socks, gloves, a hat and a scarf, and prefer synthetic and wool fabrics, which insulate better than the alternatives. Add or remove layers as you go, and remove one before you start sweating, because damp clothing stops insulating.

Three things catch visitors out more than the coat does.

  • Footwear. A city parka over ordinary sneakers is the most common visitor mistake. Sidewalks carry packed snow, meltwater and salt slush, and thin soles conduct cold straight into your feet on a fifteen-minute walk.
  • Exposed skin time. The face, ears and wrists are the parts that go numb first, and the gap between coat cuff and glove is a real one. A hat that covers the ears and a neck covering you can pull over the face change the tolerable outdoor duration substantially.
  • The indoor swing. Canadian buildings and transit are heated hard, so an outfit built for −20°C becomes uncomfortable within two minutes of entering a mall. Layers that come off easily matter as much as layers that keep heat in.

Toronto's PATH: crossing downtown without a coat

The PATH is Toronto's underground pedestrian network and it is large enough to function as a genuine winter routing tool rather than a curiosity. According to the City of Toronto, it spans more than 30 kilometres and connects more than 75 buildings, six subway stations including Union Station, three major department stores, nine hotels and destinations such as the Hockey Hall of Fame, Roy Thomson Hall, Scotiabank Arena, CF Toronto Eaton Centre, City Hall and Metro Hall, running from the waterfront to Downtown Yonge and from the Entertainment District to Yonge Street.

The catch is orientation. The PATH threads through the basements of privately owned towers, so it does not follow the street grid and its sections keep the opening hours of the buildings they pass through rather than a single published timetable. The City coordinates directional signage, maps and identity markers throughout the system, and a wayfinding system developed in 2016–2017 was installed across the network in spring 2018.

Montreal's RÉSO and the underground habit

Montreal's underground pedestrian network, known as the RÉSO, is the older and more socially embedded of the two systems. Tourisme Montréal describes it as spanning 32 kilometres beneath downtown, used by about 500,000 people daily, and connecting métro lines, commuter trains and buses along with shops, restaurants, hotels, offices, museums, theatres and universities. It began in 1962 with the underground mall at Place Ville Marie and expanded after Expo 67.

The difference from Toronto in daily use is that the RÉSO is wired into the métro rather than mainly into office towers, which makes it more useful for getting between neighbourhoods and less exclusively a lunchtime corridor. If you are staying at a downtown hotel connected to the network, a Montreal winter day can involve a genuinely small amount of outdoor walking.

Building a winter day around indoor segments

The way experienced winter travellers use these networks is not to stay underground all day but to break a long outdoor route into short ones. Instead of a twenty-minute walk across downtown in a wind chill of −25, you take an indoor segment for most of the distance and accept a three-minute crossing at the end.

That approach changes what you pack for a day out rather than for the trip. Carry the outer shell and the gloves even when the plan is indoors, because the transitions are where cold injury happens, and choose an itinerary where museums, malls, transit stations and restaurants sit close enough together that no single outdoor leg is long. Attractions that are genuinely outdoors, skating rinks, winter festivals and viewpoints, are worth doing early in the day when you are dry and warm rather than at the end of one.

What to check before you travel

Check three things rather than a general forecast: the wind chill value for the days you will be walking, whether a cold warning is in effect for that specific city, and whether snowfall or freezing rain is forecast, since precipitation disrupts travel more often than cold does. Then confirm whether your accommodation actually connects to the indoor network, because "downtown" and "connected to the PATH" are different claims.

This guide covers urban winter travel and clothing. It does not cover driving in winter conditions, winter tire requirements, which are set provincially and differ between provinces, or backcountry and mountain conditions, where avalanche and exposure risks are assessed by separate agencies.