Texas doesn’t hand you a clean shutoff switch for winter. The quietest month here is March, when heating and cooling demand together add up to about 208 degree days, a moderate number, not a true idle. Shut the furnace down for the season in March, but don’t be surprised if the air conditioner still gets called on some afternoons before spring settles in. Here’s what that number actually means, and how to handle the stretch where both systems want to run.
The quietest month in Texas
Degree days measure demand, not temperature, they tally how far the day’s average temperature strayed from 65°F, in either direction, and add it up over the month. A degree day figure tells you how hard a heating or cooling system had to work, not what the thermometer read on any given afternoon.
In Texas, March comes out as the calmest point on the calendar, with roughly 208 combined heating and cooling degree days. That places it well above the lowest quietest-month figure recorded anywhere in the country, around 70, and closer to the high end of the national range, which tops out near 246. Read against that scale, Texas doesn’t get a genuinely slow month the way some northern states do. It gets a month that’s merely less demanding than the ones on either side of it.
A changeover, not a pause
That distinction matters because March is one of only two months in the Texas calendar that clears the threshold for needing both heating and cooling in the same 30-day stretch (the other is November). So the honest answer is that there is no month here when the house asks for nothing. There’s a month when it asks for less, and asks for two different things instead of one big thing.
Picture the shape of the year in plain terms rather than numbers: a cold stretch builds through the dead of winter, eases back as the days lengthen, and nearly disappears just as a long, heavy run of cooling demand takes over for what amounts to most of the year. That cooling stretch doesn’t let go easily either, it reaches deep into fall before winter demand starts to rebuild. March sits at the narrow hinge between those two long seasons, which is exactly why it reads as quiet on paper and still keeps both systems on call.
Shutting the heat down for the year
Because March itself still carries meaningful heating demand, and because a monthly average is not a guarantee against a late cold snap, this isn’t a state where it makes sense to shut a heating system off completely for the season. The goal is to power it down in a way that’s easy to reverse, not to disconnect it as if it won’t be needed again until fall.
- Turn the thermostat down to stop calling for heat, rather than cutting power at the breaker or the switch, let the system finish its normal schedule instead of stopping mid-cycle.
- Let the current heating cycle run its course before touching anything else; don’t interrupt a blower or burner that’s already running.
- For gas-fired equipment, leave annual burner, venting and pilot checks to the manufacturer’s guidance and a qualified technician, this isn’t a routine do-it-yourself step, and the gas supply itself shouldn’t be shut off as part of a seasonal wind-down.
- Change or clean the filter now. ENERGY STAR advises to “Inspect, clean, or change air filters once a month in your central air conditioner, furnace, and/or heat pump,” and the changeover is a natural moment to start that habit for the season ahead.
- If the ductwork has a humidifier attached, shut it down too, it’s the one piece almost everyone forgets, and leaving it running after the heat stops calling wastes water and can invite moisture problems.
- Clear the area around the furnace or air handler, tidy up vents and returns, and store any portable heaters that were pulled out during the coldest weeks.
The first run of the cooling season
The best day to test the air conditioner isn’t the first hot day of the year, it’s a mild one beforehand. A fault caught on a 75-degree afternoon is an inconvenience. The same fault discovered during the first 95-degree week is a wait for a repair crew with a house that’s already uncomfortable.
- Clear leaves, mulch, grass clippings and overgrown plants from around the outdoor condenser unit, giving it open airflow on all sides.
- Check that the condensate drain line is clear so the system isn’t fighting a clog the first time it runs.
- Change or wash the filter, following the same monthly habit ENERGY STAR recommends for central air conditioners, furnaces and heat pumps alike.
- Run the system in COOL for a full cycle on a mild day, rather than waiting for the first genuinely hot one.
- Feel the air at a register farthest from the unit, not the closest one, weak airflow at the far end shows up before it shows up anywhere else.
That first check matters more here than in a lot of states, because Texas racks up an average of roughly 102 days a year at 90°F or hotter. That’s a long cooling season with little margin for a system that’s quietly underperforming. As ENERGY STAR puts it, “Airflow problems can reduce your system’s efficiency by up to 15 percent,” and a dirty filter is the single most common cause.
Most of this list is written for central air, which covers the large majority of Texas homes (about 83% run a central unit, out of the roughly 95% that have some form of air conditioning at all). The remaining share, around 16%, runs on individual equipment instead: window units, wall units, ductless mini-splits or portables. Those need their own version of the checklist, reinstalling or resetting the unit, cleaning its own filter, and checking a mini-split’s outdoor head, rather than a central condenser. And with ceiling fans present in about 88% of homes, plenty of Texas households lean on moving air before the compressor kicks on at all.
The days that ask for both
The situation is familiar even if nobody names it: heat comes on before sunrise, cooling comes on mid-afternoon, in the same house, in the same week. That’s not a malfunction. It’s what a month carrying both meaningful heating and cooling demand actually looks like on the ground.
For this guide, a month counts as asking for both when it reaches at least 50 heating degree days and at least 50 cooling degree days at the same time. That’s a threshold stated here to describe the pattern, not a category NOAA publishes, the agency reports the degree-day totals, not a “both” label. By that measure, Texas has two such months: March and November.
| Situation | What to do | Why it matters |
|---|---|---|
| Cold mornings, warm afternoons | Switch thermostat mode manually as needed rather than leaving it locked on one system | Avoids running the wrong system on a whim of the thermostat’s own logic |
| Don’t want to switch modes by hand | Use AUTO changeover, if the thermostat supports it | Convenient, but it can shift between heat and cool more often than needed, adding wear and energy use |
| Want fewer short-cycling swings | Set a wide deadband between the heating and cooling setpoints | Gives the house room to drift before either system fires |
| Mild afternoon, moderate humidity | Open the windows instead of running either system | Often the simplest and cheapest answer during these two transitional months |
The expensive mistake in a month like this is setting the heating and cooling setpoints too close together. A narrow gap means the furnace warms the house at 6 a.m., and by mid-afternoon the air conditioner is paying to cool that same air back down again, two systems working against each other inside a few hours, on the same day, in the same rooms.
And the changeover in the other direction
Heating demand in Texas doesn’t build gradually so much as arrive on a schedule tied to the calendar. Using Houston Intercontinental as the reference point, the monthly average temperature drops below the 65°F threshold NOAA uses to count heating degree days starting in November, climbs back above it in April, and peaks in January. That gives Texas roughly a five-month heating season, and it’s the point where this page hands off to the reverse checklist: cooling down, heating up.
What that pre-season list should focus on locally depends on what’s actually installed. Furnaces are the dominant heating equipment in Texas homes, at about 61%, so filter changes and manufacturer-scheduled burner inspections are the checks that matter to most households. Central heat pumps cover roughly 19% of homes and add their own item: a defrost-cycle check before the first cold snap. Boiler-based heating doesn’t have a reliable published figure for Texas, the survey suppressed that estimate rather than reporting zero, so a small number of homes running radiators or hot-water systems shouldn’t assume this list ignores them entirely. Propane accounts for about 2% of homes and is worth a supply check before the season starts, while natural gas and electricity between them power the bulk of furnaces and heat pumps across the state. The fuller version of that pre-season routine lives in the heating-season guide for Texas, where the sequence for restarting after months of running only cooling gets covered step by step.