December in Montréal, Canada, brings average daily highs of -2°C and overnight lows of -9°C in the 2016–2025 historical record. Pack for cold conditions, with warm layers for time spent outside. Overnight averages fall below freezing; check the forecast and local conditions before committing to an exposed walk or a long outdoor day.
In the record, at least 1 mm of rain or snow falls on 12 of 31 days on average, a daily chance of 38%. Give wet-weather alternatives a proper place in the itinerary. Arrange outdoor plans so you can move them between days, and pack a rain layer rather than relying on a completely dry run of weather.
The calculated day length, sunrise to sunset, averages about 9 hours. Sunshine averages 5 hours a day. Use the daylight window to plan the length of excursions, and check local sunrise and sunset times for the dates of your stay. Sunshine is a separate measure, and those hours need not arrive in one uninterrupted stretch.
For a culture-focused visit, group the places you want to see into manageable areas, with time between stops. Check each venue's opening dates before fixing the order. If food is a reason for the trip, leave time around meals rather than filling every gap with another journey. Check the places you choose for current opening hours.
January has an average daily high of -5°C, 3°C lower than December. Its historical rain-day chance is 36%, compared with 38% this month. If your dates are flexible, compare those trade-offs with the kind of days you want. Neither set of averages predicts the conditions of one particular holiday.