There is no month when heat “turns on” in the Northwest Territories, because it never fully turns off. At the Yellowknife A weather station, every single month of the year averages cold enough to need heating, even July. Demand peaks hardest in January, but the furnace in a Yellowknife home has no real off-season to speak of.
When the heating season starts in Northwest Territories
Most of Canada and the northern United States can point to a month when the mean daily temperature drops below the 18°C heating base and stays there until spring. The Northwest Territories can’t. At Yellowknife A, the 1981-2010 Canadian Climate Normals show the mean daily temperature staying below that 18°C threshold in every single month, including the warmest one on the calendar. July, the mildest month of the year here, still averages only 16.9°C, a hair under the point where a building stops needing supplemental heat. There’s no month to call the start of the season, because the season never lets go long enough to close.
What does move through the year is the intensity of demand, not its presence. Degree-days below 18°C, the standard measure of how hard a heating system has to work, climb and fall dramatically across the calendar even though they never hit zero. January carries the heaviest load, at 1,349 degree-days, the peak point in the annual cycle. Even the calmest stretch of summer, June and July, still registers real numbers, just far smaller ones.
Here is the full monthly picture, station by station, month by month, from the same thirty-year normal:
| Month | Degree-days below 18°C |
|---|---|
| January | 1,349 |
| February | 1,153 |
| March | 1,077 |
| April | 700 |
| May | 414 |
| June | 146 |
| July | 58 |
| August | 130 |
| September | 323 |
| October | 610 |
| November | 953 |
| December | 1,233 |
One caution matters more here than almost anywhere else in this series: these are thirty-year averages, not forecasts and not calendars. A normal tells you what a typical July looks like across three decades of records at one station. It says nothing about the particular cold snap that might hit a specific week this year, in either direction. The shape of the table is reliable. The exact week a furnace kicks in for good is not something any normal can promise.
How hard the winter works here
Add up all twelve months at Yellowknife A and the annual total comes to about 8,147 heating degree-days below 18°C. Degree-days work as a rough stand-in for fuel use: a house that sees roughly twice the degree-days of another, similar house, burns roughly twice the fuel to stay comfortable, all else being equal. An annual figure north of 8,000 puts this territory firmly among the hardest-working heating climates measured this way.
What the yearly total can’t show is the shape of the burden, and that’s exactly what the monthly table above is for. Two places can post similar annual totals while living through completely different winters, one with a long, gently cold season, the other with a short, brutal one concentrated in a handful of weeks. The Northwest Territories numbers show something closer to the second pattern layered onto a season that simply never ends: a sharp climb from autumn into a hard January-February core, then a slow retreat that never actually reaches zero. That distinction matters for anyone comparing this climate to somewhere else, because a raw annual number hides it completely.
One thing this figure cannot do is travel across the border. It’s counted on an 18°C base over the 1981-2010 period, following Environment and Climate Change Canada’s methodology. Heating degree-day figures published for U.S. locations use a 65°F base and the 1991-2020 period. The units, the base temperature, and the measurement window all differ, so lining up a Canadian total next to an American one produces a number that looks like a comparison but measures nothing real.
What most homes in Northwest Territories actually heat with
Statistics Canada’s most recent survey covering the territories, taken as of December 31, 2012, found two systems doing most of the work in Northwest Territories households:
| Heating system | Share of homes |
|---|---|
| Hot-air furnace | 56% |
| Steam or hot-water furnace | 30% |
Figures for electric baseboard heat, wood stoves, and other equipment weren’t reported separately for the territory that year, which isn’t the same as saying nobody uses them. It means the sample was too small, or too scattered, to publish a reliable estimate for those categories. Anyone burning wood as a backup or primary source should look at the companion wood-heating guide for this territory rather than assume the gap in this table means zero.
That 56% share for hot-air furnaces reflects what got installed decades ago, largely tracking whatever fuel was affordable when the housing stock went up. It isn’t a verdict on what works best in a Northwest Territories home today, and it shouldn’t be read as one.
Practically speaking, a forced-air furnace heats a room fast, distributes air through the whole house from one central unit, and depends entirely on a filter and duct system that most homeowners never look at until something goes wrong. The one maintenance item it punishes hardest for being skipped is the filter: a clogged one restricts airflow, strains the blower motor, and can shorten the life of the whole unit. Hot-water and steam systems, radiators fed by a boiler, run quieter and hold heat longer after they shut off, but they need bled radiators and a checked expansion tank to avoid cold spots and knocking pipes.
Run it once before you need it
With a heating season that runs the calendar year round here, the smart window to test everything is early autumn, September or October, well before demand climbs toward the January peak and before every technician in the territory is booked solid. Work through the system in this order:
- Turn the thermostat up a few degrees above room temperature and run a short cycle, just to hear whether the system starts cleanly, without banging, squealing, or a delayed ignition.
- Expect a burnt-dust smell on the first firing of the season. That’s normal, it’s just dust burning off the heat exchanger, and it should clear within a few minutes.
- Replace or clean the furnace filter. This is the cheapest step on the list and the one most likely to get skipped.
- Walk the house and clear anything blocking a vent, a radiator, or an outdoor heat pump unit, furniture, curtains, boxes stacked in a basement corner.
- Test every carbon monoxide alarm in the house. A combustion furnace that isn’t venting properly can push CO into living space without warning, and a working alarm is the only defense that matters here.
- If the system won’t hold a cycle, trips a breaker, or the CO alarm sounds during the test, stop and call a licensed technician rather than troubleshooting further.
Even a furnace that passes every one of those checks can still lose a surprising amount of heat before it reaches a room. According to the U.S. Department of Energy, “in a typical house, about 20%-30% of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts.” That’s air escaping through the ductwork itself, not a measure of the whole house’s heat loss, but it explains a lot about rooms that never quite warm up and bills that don’t match the thermostat setting.
What turning it down is actually worth
The Department of Energy puts a specific number on the payoff of a thermostat setback: “You can save as much as 10% a year on heating and cooling by simply turning your thermostat back 7-10°F for 8 hours a day from its normal setting.” That figure covers both heating and cooling combined, over a full year, for that specific setback held for that specific stretch of hours. It isn’t a per-degree rule, and stretching it into one overstates the savings.
In a territory where the heating side of that equation runs essentially year-round, the setback has far more hours to work with than it would somewhere with a short winter and a long shoulder season. A programmable thermostat set back overnight or during an empty workday isn’t a seasonal trick here, it’s a habit that pays out across nearly every month on the table above, including the ones that look mild by comparison.