Pellet Grill Temperature Swings: How Much Is Normal?

Two manufacturers publish the same number. Traeger says a grill in good weather should fluctuate no more than about 25°F either side of the setting, and Pit Boss says a swing of roughly 25°F is completely normal. So if what you are watching is a wobble of twenty degrees, nothing is wrong. The harder question is whose number you are actually watching, because a pellet grill has at least three thermometers and they are not measuring the same thing.

The number both makers publish

Traeger’s own support documentation is unusually direct about this. Temperature swings are normal, and by design: the controller runs an algorithm specific to each model, and on a typical good-weather day the grill should fluctuate no more than 25°F either way. Beyond that, Traeger treats it as a problem worth investigating.

Pit Boss arrives at the same figure by describing the mechanism rather than the tolerance. Its controller holds temperature by switching the auger on and off at intervals, which it says produces a swing of about 25°F and is completely normal.

Those are two companies with no reason to agree, publishing the same tolerance from opposite directions — one from what the algorithm targets, the other from what the hardware does. Twenty-five degrees is the working answer to “is my grill broken.”

Two useful riders come with it. Traeger notes that fluctuations get larger at low temperatures and larger again on its Super Smoke setting, and that this is deliberate, because the varying fire is part of what produces smoke flavour. So the long, low cook where the swings look worst is the cook where they are most expected.

Which thermometer is telling you this?

This is the part almost nobody covers, and it changes the diagnosis more than anything else on the list.

A pellet grill typically has a sensor wired to the controller, often a dial in the lid, and whatever probe you have added yourself. They disagree, and they are supposed to.

The controller is averaging, not holding a point

Traeger states that its grills cook on an average: the displayed temperature is an estimate of the middle of the grill, built from data collected at many points across the grates, and the fluctuations average out to the set temperature. Pit Boss describes its own control-board probe the same way, as taking an average across the cooking chamber.

A thermometer you place yourself does not do that. It reads one point. Traeger’s position is blunt: even if you put a probe exactly where the grill’s own sensor sits, you will get a different value, because the reading depends on the sensor’s shape, mass, orientation and the radiant heat around it.

The dial in the lid is the least reliable of the three

If the swing you are worried about is the needle in the lid, treat that as a measurement problem first. Pit Boss states that a dome thermometer differing from the control board reading by up to 100°F is normal. It sits at the top of the chamber in the hottest, most turbulent air, and it is a cheap mechanical gauge rather than a calibrated instrument.

Where this argument comes from, and who benefits

Traeger has an obvious interest in owners trusting its controller over a probe bought elsewhere, and it is worth saying so rather than presenting the company as neutral. This site has the opposite interest: it earns commission when readers buy thermometers.

The technical claim survives both. A controller estimating an average across a whole cooking surface and a probe reading one spot six inches away will genuinely disagree, and neither is lying. What follows is not that you should throw the probe away — it is that a disagreement between two instruments is not evidence of a fault, and that the probe earns its keep by telling you about the food rather than by auditing the controller.

What a real swing looks like

Something is genuinely wrong when the pattern stops looking like a wobble and starts looking like a failure to recover.

• Swings much wider than 25°F on a mild, still day, with the lid shut.
• The temperature climbing and not coming back down, or falling and not recovering.
• The fire going out mid-cook.
• Wild movement that started suddenly, on a grill that used to hold steady.

Anything that only appears in wind, in cold, at the lowest setting, or right after the lid has been open belongs in the normal column until proven otherwise.

Pellets, which both makers put first

Traeger names low-quality or old pellets as the number one cause of temperature management issues, and the test it gives is a physical one rather than a brand preference. Pull a few pellets from the end of the auger or out of the firepot. Good ones have a sheen and snap cleanly. Ones that crumble or look dull have taken on moisture and should be replaced.

The other half of the same problem is the dust at the bottom of the hopper. Sawdust will not ignite, so once it starts feeding through the auger into the firepot the fire becomes intermittent and the temperature follows it.

Pit Boss explains what damp does structurally: water makes pellets swell, disintegrate and then harden, which is how an auger ends up jammed. That is worth knowing because a jammed auger and a temperature swing have the same root cause, and the swing usually shows up first.

Storage is therefore the fix that prevents most of this. A hopper lid keeps light rain off but not much more, so pellets are better kept in a sealed container indoors, and a hopper left loaded through a wet week is asking for trouble.

Air, ash and the things that choke the fire

A pellet grill is a small forced-draught fire, and anything that restricts air destabilises it.

The chimney. Traeger asks for a thumb-size gap between the bottom of the cap and the chimney. Pit Boss goes further and says to raise the cap as high as it will go. Screwing the cap down to keep smoke in is the same instinct that ruins an electric smoker, and it has the same effect here.

Crowding. Traeger asks for an inch of clearance from the edge of the grill when placing food or large pans, because a full-width tray turns the cooking chamber into a baffle and the air stops moving the way the controller expects.

Foil. Both a foil drip liner and a damaged or missing drip tray or heat baffle appear on Traeger’s list of contributors. The baffle is what stops the fire radiating straight at the sensor; without it, or with foil changing how heat moves, the controller is reacting to the wrong thing.

Ash. Pit Boss recommends cleaning after every 40 to 60 pounds of pellets, vacuuming ash out of the firepot and the base. A firepot half full of ash cannot hold a steady fire.

The things you are doing

Three habits produce most of the remaining swings, and all three are free to stop.

Opening the lid. Every opening dumps the chamber heat, and the controller then works to bring it back — which looks exactly like an overshoot because it partly is one. Both makers list it.

Changing the set temperature often. The algorithm is chasing a moving target, and each change starts the recovery cycle again.

Starting or shutting down incorrectly. Traeger lists this explicitly. A startup cycle that is interrupted, or a shutdown that does not run its course, leaves unburnt pellets in the firepot, and the next cook begins with the wrong amount of fuel already in place.

Weather, which is not a fault

Traeger’s tolerance is stated for a typical good-weather day, which is an admission in itself. Cold raises the work the fire has to do and wind strips heat from the walls continuously, so both widen the swing without anything being broken.

Moving the grill out of a draught does more than any part will. If the machine only misbehaves on cold or windy days and holds steady on mild ones, that pattern is the diagnosis.

When it is a part

Once the pellets are dry, the firepot is clean, the chimney is open, the lid has stayed shut and the weather is mild, a short list is left: the temperature sensor itself, the combustion fan, and the auger motor. All three are replaceable on most grills, and all three are worth confirming against the manufacturer’s own troubleshooting steps for your model rather than a general guide, because the procedures are specific to the controller.

That is also the point at which a support ticket beats another afternoon of guessing. Both companies publish model-specific diagnostics and sell the parts.

The order worth working through

1. Establish which thermometer is reporting the swing — the controller, the lid dial, or a probe you added.
2. If it is the lid dial, stop there and compare it against the controller before doing anything else.
3. Measure the size of the swing. Under about 25°F on a mild day is normal on both brands.
4. Note the conditions: wind, cold, the set temperature, whether a smoke setting is on.
5. Check the pellets for sheen and snap, and the hopper for sawdust.
6. Vacuum the firepot and check the drip tray and baffle are present and unfoiled.
7. Open the chimney cap and give food an inch of clearance from the edges.
8. Run a cook without opening the lid and without changing the setting.
9. If it still swings wildly, or will not recover, treat the sensor, fan or auger as the remaining suspects and use the maker’s model-specific guidance.

The order runs from free to expensive, not from most likely to least likely. Neither manufacturer publishes failure-rate data, and a percentage invented here would be worth nothing.

If the grill will not light at all rather than swinging once lit, that is an ignition question rather than a control one, and it is covered in a grill igniter clicking but not lighting.

Cook to the food, not to the display

The practical conclusion of everything above is that the grill’s number and your number will differ, and neither of them is the thing you actually care about, which is the internal temperature of the meat.

A leave-in probe earns its place there rather than as an auditor of the controller, and an ambient sensor alongside it is useful for spotting the difference between a wobble and a fire that has gone out. The options are in the guides to meat thermometers for smoking and BBQ thermometers, which has a section on pellet grills specifically. Whichever you use, check it in iced and boiling water first — the method is in how to calibrate a meat thermometer, and there is no sense arguing with a controller using an instrument you have not verified.

A different machine with a different problem: if the cabinet in question is an electric smoker that never reaches its setting at all, that is covered in an electric smoker not getting hot enough. The rest of the outdoor cooking guides are collected on the outdoor cooking hub.

How This Guide Was Put Together

Plainly: this is a research-based guide, not a hands-on test. I do not own a pellet grill, nothing here is a report from my own garden, and no cook was instrumented to produce these figures.

What it rests on is manufacturer documentation, read at source rather than repeated from other guides. Traeger’s support articles on temperature swings and on third-party thermometers supply the 25°F tolerance, the averaging explanation, the pellet test and the airflow requirements. Pit Boss’s FAQ independently supplies the same 25°F figure, the auger-cycling mechanism behind it, the 100°F dome thermometer tolerance, the damp-pellet failure mode and the cleaning interval.

Where a source has an interest, it is named in the text rather than hidden. Traeger’s argument against third-party thermometers serves Traeger, and this site earns commission on thermometers, so both sides of that argument come from somewhere.

Also not established: whether 25°F is a reasonable tolerance for brands other than these two. Both figures are each company’s statement about its own grills, they happen to agree, and that agreement is suggestive rather than a standard. Several makers publish nothing at all, and no independent body tests pellet grill temperature stability, so an owner of a third brand has only the manual to go on.

Frequently Asked Questions

How much temperature swing is normal on a pellet grill?

About 25°F either side of the setting. Traeger states a grill in good weather should fluctuate no more than that, and Pit Boss says a swing of roughly 25°F is completely normal because its controller cycles the auger on and off. Both figures are each company’s statement about its own grills, but they agree.

Why does my thermometer disagree with the grill controller?

Because they are measuring different things. Traeger says its grills cook on an average, estimating the temperature in the middle of the chamber from data taken across the grates, while a probe you place reads one specific point. Traeger adds that even a probe placed exactly where the built-in sensor sits will read differently.

Is a 100 degree difference on the lid thermometer normal?

On a Pit Boss, yes. The company states that a dome thermometer differing from the control board reading by up to 100°F is normal. The dial sits in the hottest, most turbulent air at the top of the chamber and is a cheap mechanical gauge, so it is the least reliable of the readings available to you.

Why are the swings worse on the smoke setting?

Because they are meant to be. Traeger states that fluctuations get larger at low temperatures and larger again on Super Smoke, and that the varying fire is a key part of producing smoke flavour. The long low cook where the swings look most alarming is the one where they are most expected.

Can bad pellets really cause temperature swings?

Both makers put fuel first. Traeger calls low-quality or old pellets the number one cause of temperature management issues, and says good pellets have a sheen and snap cleanly while damp ones crumble and look dull. Sawdust in the hopper will not ignite at all. Pit Boss adds that water makes pellets swell and then harden, which jams augers.

When should I stop troubleshooting and contact the manufacturer?

When the grill swings far beyond 25°F on a mild, still day with dry pellets, a clean firepot, an open chimney and the lid shut — or when it climbs or falls and does not recover. At that point the sensor, the combustion fan or the auger motor are the suspects, and the diagnostics are specific to your controller.