In Wyoming, the heat almost never gets a true day off. August comes closest, but even then the house is still asking for something. What actually exists here are two changeover points, one as summer opens and one as it closes, plus a single month, June, when the furnace and the air conditioner both get called on in the same week.
The quietest month in Wyoming
August is the calmest month on the calendar here, at least by the numbers. Combined heating and cooling degree days for August come to about 163, according to NOAA’s 1991-2020 climate normals. Nationally, the quietest month anywhere in the fifty states runs as low as roughly 70 and as high as about 246, so 163 lands closer to the middle of that range than to either edge.
Degree days aren’t a temperature. They measure how much a house is calling on its heating or cooling to make up the difference between the outdoor air and a 65-degree baseline, so a bigger number means more demand that month, not a hotter or colder one.
A total of 163 is not the mark of a true pause. States with the lowest quietest-month figures, closer to 70, get stretches of real quiet, weeks where a thermostat could sit untouched. Wyoming’s number sits well above that, which is an honest way of saying there is no month here when the house asks for nothing. Winter runs long and heavy, summer arrives late and leaves early, and the gap between the two never fully goes slack, it just goes softer for a few weeks in August.
That softness has a limit, too. The reference station at Cheyenne averages about 10.4 days a year at 90 degrees or hotter, a small but real number that shows up even in what statistically counts as the mild season. So August reads as the least demanding month on paper, and it is, but it’s a lull inside a busy year, not a break from it.
Shutting the heat down for the year
Winding the furnace down at the end of its season is less about flipping a switch and more about letting the system stand down in the right order, so nothing gets left half-finished. Here’s a sequence that works for most Wyoming homes:
- Set the thermostat so it stops calling for heat, rather than cutting power at the breaker or the switch.
- Let the system finish out its current cycle on its own instead of interrupting it mid-run.
- Have any fuel-burning equipment, its venting, and its carbon monoxide detector checked according to the manufacturer’s guidance, which is the authority on how that particular unit should be handled at shutdown, not a general rule to shut off gas or a pilot yourself.
- Change or clean the filter. ENERGY STAR’s own maintenance advice is blunt about how often this should happen: “Inspect, clean, or change air filters once a month in your central air conditioner, furnace, and/or heat pump.” That instruction covers all three pieces of equipment together, so a heat pump owner needs it as much as a furnace owner does.
- If the ductwork carries a whole-house humidifier, shut it down and drain it. It’s the step almost everyone forgets, and a humidifier left wet and idle all summer is an invitation to mineral buildup and mold.
- Finish with the physical tidy-up, clear vents and registers of anything stacked in front of them over the winter, and vacuum out visible dust near the unit.
One caution worth stating plainly for this state: don’t treat “shutting down for the year” as disconnecting the system outright. Wyoming’s heating season, by NOAA’s own count, still shows measurable demand in June, so a cool morning that late in spring can still call for heat. Turning the thermostat down and letting the system stand idle is the right move; leaving it physically unable to respond is not, not here.
The first run of the cooling season
The best day to test the air conditioner is a mild one, not the first 90-degree afternoon of the year. A fault caught on a comfortable day gets fixed on your schedule. The same fault discovered during the first real heat wave gets fixed on nobody’s schedule, usually with a wait.
A short checklist covers most of what matters before the season turns:
- Clear leaves, grass clippings, and anything else crowding the outdoor unit, giving it at least a couple of feet of open space on every side.
- Check that the condensate line drains freely, with no blockage that would back water up into the system.
- Change or wash the filter, following the same ENERGY STAR guidance already mentioned for the furnace.
- Run the system in COOL for a full cycle on a mild day, not a hot one, and listen for anything that sounds wrong.
- Feel the air coming out of a register at the far end of the house, not the one closest to the unit, since that’s the one most likely to reveal a weak airflow problem.
That last step matters more than it looks. ENERGY STAR notes that “airflow problems can reduce your system’s efficiency by up to 15 percent,” which means a unit can be running, cooling, and still quietly underperforming without anything sounding broken.
What this checklist looks like in practice depends on what’s actually installed. In Wyoming, about 71% of homes have some form of air conditioning, but only 40% run a central system, according to the Energy Information Administration’s Residential Energy Consumption Survey. Another 23% rely on individual equipment, a window unit, a wall unit, a ductless mini-split, or a portable, and that’s a different maintenance list: filter and drainage checks still apply, but there’s no outdoor condenser pad to clear and no whole-house condensate line to inspect. Roughly 29% of Wyoming households have no mechanical air conditioning installed at all, and with ceiling fans in about 63% of homes, that combination does a fair amount of the summer work here. With only about 10.4 days a year above 90 degrees at the reference station, it’s tempting to skip the pre-season check entirely, but that low frequency is exactly why the system needs to be confirmed working before one of those few hot days arrives.
The days that ask for both
June is the month Wyoming homeowners recognize without needing a chart for it, a morning cool enough for the furnace to kick on before sunrise, an afternoon warm enough for the air conditioner to answer back a few hours later. NOAA’s normals put June at about 115 heating degree days and 56 cooling degree days, and by a simple convention stated here, not a published NOAA category, any month with at least 50 of each counts as asking for both. June clears that bar comfortably.
A month like that isn’t a contradiction in the equipment. It’s a house that genuinely needs two different things within the same 24 hours, and the thermostat setup either handles that cleanly or fights itself trying.
| Thermostat approach | What it does | Trade-off |
|---|---|---|
| Manual mode switching | You choose HEAT or COOL by hand, morning and afternoon | Most efficient, but only if someone remembers to switch it |
| AUTO changeover | The thermostat switches modes on its own between two setpoints | Convenient, but a narrow gap between the two setpoints means the system can heat in the morning and then cool the same air it just paid to warm |
| Wide deadband | A gap of several degrees between the heating and cooling setpoints | Lets the house drift naturally instead of the system fighting itself over a one- or two-degree spread |
| Open windows | No equipment running at all | Often the simplest, cheapest answer on a June afternoon that isn’t actually that hot |
The expensive mistake is a narrow deadband on AUTO, something like a 68-degree heat setpoint and a 70-degree cool setpoint. That gap is so tight the system swings between the two all day, paying to heat the air in the morning and then paying again to cool that same air a few hours later. Widening the gap, or just switching to manual for a week in June, usually costs nothing and saves a fair amount.
And the changeover in the other direction
Heating season in Wyoming starts earlier than most people expect. By NOAA’s normals, September is the first month where the average temperature at Cheyenne drops below the 65-degree baseline used to count heating degree days, and once it starts, it doesn’t let go easily, running roughly ten months before the mean climbs back above 65 in July. December is the peak, at about 1,125 heating degree days, the heaviest month on the entire calendar here.
What that means for the fall changeover depends on what the house actually burns. In Wyoming, the EIA survey shows about 68% of homes heat with a furnace and 71% run on natural gas, so most of the fall checklist is furnace territory: filter, ignition, and a working carbon monoxide detector near the unit. About 9% of homes run a steam or hot-water boiler instead, which means bleeding radiators and checking the expansion tank rather than swapping a filter. The survey doesn’t publish a reliable figure for central heat pumps in this state, and that’s a gap in the data, not a sign that none exist.
The full pre-heating checklist, including the specific order of operations, belongs on this site’s heating-season guide rather than repeated here. What matters for now is timing: given how early September demand actually shows up at the reference station, the smart move is running that checklist in late summer, not waiting for the first cold snap to force the issue.