In Quebec, the heat can safely go quiet for a few weeks in June, when the average temperature finally climbs back above 18°C and neither furnace nor air conditioner has much to do. It’s a short window: with heating degree-days recorded from September clear through May, most of the year here still asks for warmth. June is the exception, not the rule, and even then the pause doesn’t last long.
The quietest month in Quebec
June is the quietest month for home heating and cooling in Quebec. Combined, heating and cooling degree-days at Montreal-Pierre Elliott Trudeau International Airport add up to about 90 for the month, a figure that sits on the low side of the national range this site tracks, which runs from roughly 45 in the calmest provinces and territories to as high as 233 in the busiest.
What the number actually measures
That total isn’t a temperature: a degree-day measures how much demand a building has for heating or cooling on a given day, added together across the month. A low total means the thermostat spent most of June doing very little, not that the weather itself hit some fixed mild mark on a thermometer.
A figure near 90 puts Quebec closer to the genuinely quiet end of that national scale than to the crossover states and provinces where furnace and air conditioner trade places within the same week. That distinction matters. It means June here comes closer to an actual rest for the equipment than a hand-off from one system to the next. The heating season stretches from September through May, nine months by the measure used on this site, so by the time June arrives the furnace has already been earning its keep for the better part of three-quarters of the year.
The shape of the rest of the year
Summer itself runs mild and short. Days that push an air conditioner hard are rare here, which keeps the cooling side of the ledger light even once June gives way to July and August. Picture the year as a long, slow climb into cold that peaks in the dead of winter, a gradual thaw through spring, a brief flat stretch where the house needs almost nothing from either system, and then the cold building again in early fall. That flat stretch is June. It’s short, and it doesn’t stretch the way it might in a province with a longer, hotter summer, but for anyone looking for the moment to shut the furnace down for the year, this is it.
Shutting the heat down for the year
June’s lull is the right moment to shut heating down for the season, but the order matters more than most homeowners assume. Doing it out of sequence risks a system that starts up again in the fall with a problem nobody caught while the weather was still easy to work in.
The steps, in order
- Stop calling for heat at the thermostat first, rather than cutting power at a breaker or switch. Lower the target so the system stops firing on its own.
- Let the system finish whatever cycle it’s already running. Cutting power mid-cycle on a furnace can leave a blower running with no heat source, or leave a boiler holding pressure it wasn’t meant to sit at.
- Check anything that burns fuel to heat the home for anything visibly amiss, but leave the actual gas supply and pilot assembly alone. Shutting those off, or relighting them, is governed by the manufacturer’s guidance for that specific appliance, and going further than a visual check belongs to a technician, not a seasonal routine.
- Deal with the filter. U.S. ENERGY STAR guidance is direct: “Inspect, clean, or change air filters once a month in your central air conditioner, furnace, and/or heat pump.” The shutdown is a natural point for that last check of the season, even in a home running a heat pump instead of a furnace.
- Shut down the humidifier if one is fitted to the ductwork. It’s the step almost everyone forgets, and one left running into a season it wasn’t built for can flood a duct or crack a part never designed for summer humidity.
- Finish with the physical tidy-up: clear vents and returns of anything stacked in front of them over the winter, vacuum out visible dust near the unit, and give the equipment room to sit idle for a few weeks.
One caution belongs before the list, not after. With heating demand here stretching from September into May, a full shutdown that leaves a house with no heat source available at all is never really advisable, even during the quiet stretch. An empty house, or a cool night arriving earlier than the calendar suggests, can still put pipes at risk. Setting the thermostat back and letting the system rest is not the same as disabling it entirely.
The first run of the cooling season
The best day to start the air conditioner for the year is a mild one, not the first genuinely hot afternoon. A mild day leaves room to catch a fault, a stuck fan, a clogged drain line, before living through a heat wave with a system that isn’t working right.
- Clear the outdoor unit and the space around it of anything that piled up over winter, leaves, mulch, a stray tarp, within roughly two feet of the cabinet.
- Check the condensate path. A blocked drain line is one of the most common reasons a cooling system underperforms or leaks in its first weeks of use.
- Change or wash the filter, on the same monthly rhythm ENERGY STAR recommends for the equipment.
- Run the system in COOL for a full cycle on a mild day, letting it settle into steady operation rather than switching it off after a few minutes.
- Feel the air at a register far from the unit, not the closest one. A weak reading at the far end of the house often shows up before anything else does.
ENERGY STAR is blunt about what a skipped filter costs: “Airflow problems can reduce your system’s efficiency by up to 15 percent.” That’s a system in otherwise perfect working order, quietly underperforming because of one overlooked part.
What’s actually running the cooling
How much of this list applies depends on what’s actually cooling the house. Statistics Canada puts air conditioning in 69.3% of Quebec households, just above the national rate of 68.3%, though the survey doesn’t break that figure down by central systems versus window or portable units. A household with central cooling, often paired with a heat pump given how common those have become in the province, gets the full checklist above. A household running one or two individual units room by room has a shorter version: check the filter, check where the water drains, and run each unit for a while on a mild day before the first real heat arrives. Either way, a low ownership rate in a given area doesn’t necessarily mean a mild summer; it can just as easily reflect older housing stock that was never built with cooling in mind.
The days that ask for both
There’s a stretch, usually right around that quiet month, when a house calls for heat before sunrise and asks for cooling by mid-afternoon, sometimes on the same day. For this site, a month counts as asking for both when it carries at least 50 heating degree-days and at least 50 cooling degree-days in the same thirty days. That threshold isn’t a category Environment and Climate Change Canada publishes; it’s a convention used here to describe the overlap plainly, nothing more.
Handled badly, this stretch is where energy bills spike for no good reason. Handled well, it mostly comes down to thermostat settings.
| Situation | What to do |
|---|---|
| Thermostat mode | Switch manually between HEAT in early morning and COOL in the afternoon rather than leaving one fixed mode running all day. |
| AUTO changeover | Lets the system pick heat or cool on its own around a setpoint, convenient day to day, but it can mean more short cycles and more total run time than switching by hand. |
| Wide deadband | A gap of several degrees between the heating setpoint and the cooling setpoint keeps the system from firing one right after the other; it’s the simplest fix for this stretch of the year. |
| Open windows | On the mild days that make up most of June here, opening windows in early morning and evening covers a wider stretch than either system needs to run at all. |
The mistake to avoid costs real money: a narrow gap between the two setpoints, say a single degree between where heat kicks in and where cooling kicks in, means the furnace warms the house at dawn and the air conditioner spends the afternoon cooling down the same air it just paid to heat. Widening that gap costs nothing and makes the difference between a house that runs efficiently through this stretch and one that fights itself twice a day.
And the changeover in the other direction
September is when the reverse begins. It’s the first month of the year whose average daily temperature drops back below 18°C, the same threshold that marks when heating degree-days start piling up again, opening a heating season here that runs all the way through May.
What’s installed decides what to check
The autumn version of the checklist above is shorter, and what matters most depends on what’s actually installed. Electric baseboard heaters are the main system in 54% of Quebec homes, by far the largest share, with no combustion or fuel line to inspect: the pre-season check there is mostly clearing furniture and curtains away from the units and confirming nothing tripped over the summer. Heat pumps, the main system in 16% of homes, need the reverse-cycle switch tested before the first cold night rather than during it. Forced-air furnaces sit at 11% and boilers at 4%, and both carry the combustion and venting checks that baseboard heat doesn’t need at all. A remaining share runs on heating stoves, at 2%, with chimney and fuel checks of their own. These shares come from a 2023 Statistics Canada survey of primary heating systems and shouldn’t be lined up against similar-looking figures from U.S. sources, which measure things differently.
The detail behind each of those checks, what to inspect on a furnace before the first cold snap, how to test a heat pump’s reversing valve, belongs in the heating-season guide for Quebec rather than here. This page’s job ends at the handoff: June closes the loop, September opens it again.