In Vermont, the heating season opens in September, the first month when Burlington’s normal mean temperature slips below the 65°F line that meteorologists use to count heating degree days. Demand climbs through fall, peaks in January, and the season stretches across roughly nine months before the mean temperature climbs back above 65°F in June.
When the heating season starts in Vermont
That 65°F threshold isn’t arbitrary. It’s the base the National Oceanic and Atmospheric Administration uses nationwide to calculate heating degree days, a measure of how far, and for how long, the air falls short of a comfortable indoor temperature. At Burlington International Airport, the reference station for this data, September’s normal mean temperature of 62.7°F is the first to dip under that line, which is why the season effectively opens then, even if furnaces around the state don’t fire up in earnest until the first real cold front rolls through.
A monthly normal is a 30-year average, not a forecast for any particular week. Some Septembers stay mild well past Labor Day; others bring a hard frost before the month is out. The number marks a pattern, not a date on your calendar.
The table below shows how the season actually unfolds, month by month, in heating degree days at the Burlington station.
| Month | Heating Degree Days |
|---|---|
| January | 1,367 |
| February | 1,179 |
| March | 1,016 |
| April | 586 |
| May | 236 |
| June | 50 |
| July | 6 |
| August | 15 |
| September | 134 |
| October | 459 |
| November | 773 |
| December | 1,142 |
Every month of the year carries at least a few heating degree days here, so there’s no true dead stretch when a furnace could sit untouched. January stands as the coldest month of the normals; September marks the start of the climb. Everything in between is right there in the numbers above.
How hard the winter works here
Add up those monthly figures and Burlington lands at about 6,960 heating degree days a year, against roughly 656 cooling degree days. That lopsided ratio tells the real story: this is a place built around keeping heat in, not keeping it out. Air conditioning is a summer convenience here; heating is the system that does the heavy lifting all year.
Degree days work as a rough stand-in for fuel use. A house that logs twice the degree days of another, all else being equal, burns roughly twice the fuel to stay comfortable. Vermont’s total sits high enough that a house here, sized identically to one in a milder state, will simply ask more of its furnace, its boiler, or its heat pump over the course of a year.
What the annual number can’t show is shape. Two places can share the same yearly total while one endures a short, brutal freeze and the other a long, mild grind. The monthly table above answers that question for Vermont directly: this is a long season with a hard middle, not a short cold snap padded by a mild shoulder. January and December each rack up over a thousand degree days on their own, and the season doesn’t really loosen its grip until April.
What most homes in Vermont actually heat with
Federal survey data on home heating equipment in Vermont shows a state still leaning on older systems and traditional fuels rather than newer electric options.
| System / Fuel | Share of Homes |
|---|---|
| Furnace | 51% |
| Steam or hot-water boiler | 25% |
| Fuel oil or kerosene | 46% |
| Natural gas | 21% |
| Propane | 13% |
| Electricity | 6% |
Central heat pump adoption wasn’t reported in enough numbers to publish a reliable figure for the state, which doesn’t mean nobody runs one, just that the survey sample was too thin to count it with confidence.
A share of homes tells you what got installed decades ago, when a given fuel was cheap and available, not what’s actually the best fit for a house today. Reading it as a recommendation would be a mistake.
Furnaces, which lead the pack, push heated air through ductwork and respond quickly, good for a fast recovery after a cold night, but they depend entirely on that ductwork staying sealed and clean. The one maintenance item that punishes skippers is the air filter: a clogged one restricts airflow, forces the blower motor to work harder, and can shorten the system’s life by years. Boilers, which heat roughly a quarter of Vermont homes through radiators or baseboard, hold heat longer and run quieter, but they’re slower to respond and need their own annual attention, particularly bleeding air from the lines and checking the pressure relief valve. Fuel oil, still the single most common heating fuel in the state, requires a tank that gets checked for leaks and a burner that gets cleaned yearly to avoid soot buildup. This is a subject worth its own look, and the state’s wood-heating guide covers it in more depth for households considering a switch.
Run it once before you need it
A heating system doesn’t usually fail in July. It fails on the first genuinely cold night of the year, which in Vermont tends to land sometime after that September threshold passes and the first hard frost hits. That’s exactly when every technician in the state is already booked solid. The fix is to test the system weeks earlier, in September, while there’s still slack in everyone’s schedule.
- Turn the thermostat down, then back up above room temperature, and let the system run a short cycle while you listen. Rattling, grinding, or a burner that won’t catch on the first try are all signs worth noting before the real cold arrives.
- Expect a faint burnt-dust smell the first time the system fires after months of sitting idle. That’s dust burning off the heat exchanger or coils, and it’s normal, it should fade within a few minutes and not return on later cycles.
- Check the filter and swap it if it’s gray or clogged. This is the cheapest, fastest step on the list, and it protects the blower motor from the strain that shortens its life.
- Clear at least a couple feet of space around vents, radiators, or the outdoor unit if you run a heat pump. Furniture, curtains, and stored boxes block airflow and make the whole system work harder for less heat.
- Test the carbon monoxide alarm. Combustion heating systems, furnaces, boilers, and fuel oil burners alike, can leak carbon monoxide if something’s gone wrong with venting, and a working alarm is the cheapest insurance in the house.
- If the system won’t hold a cycle, trips a breaker, or the burnt smell doesn’t clear, stop testing and call a technician before the season gets busy.
Even a system in perfect working order isn’t delivering all its heat to the 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, and the heat riding along with it, escaping into a basement, attic, or crawlspace before it ever reaches a living room, which is worth remembering the next time a room upstairs never quite warms up the way the thermostat suggests it should.
What turning it down is actually worth
The Department of Energy is specific about what a thermostat setback actually buys a household: “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’s a yearly figure covering both heating and cooling, tied to that particular setback and that particular stretch of hours, not a per-degree formula that can be scaled up or down.
In a place where the heating season runs about nine months and cooling barely registers, nearly all of that saving comes from the winter side of the equation. A setback held overnight or during a workday has more hours to work with here than it would in a state with a shorter, milder season, simply because Vermont’s furnaces and boilers are running for so much more of the year in the first place.