Humidor Not Holding Humidity: Causes and How to Fix It

Check the gauge before you change anything else, then work down this list.

1. Calibrate your hygrometer: Verify whether your relative humidity (RH) reading is accurate by testing your gauge against a known benchmark before you alter anything else.
2. Test the lid seal: Check whether ambient air is entering through a loose joint or loose lid, which bleeds moisture into the surrounding room.
3. Check the wood seasoning: Determine whether dry Spanish cedar is absorbing humidity directly out of the air and pulling moisture away from your cigars.
4. Review humidifier capacity and fluid: Confirm that your humidification device contains enough active surface area and fluid for the rated cigar count of the box.
5. Assess the room conditions: Examine whether temperature swings, direct sunlight, heating vents, or low external humidity are stressing the container.
6. Account for new cigars: Check whether a recent batch of dry sticks was introduced all at once, which temporarily draws down the ambient moisture.

According to Northwoods Humidors, you must confirm that the hygrometer is calibrated and reading correctly before you inspect the box seal or attempt repairs.

Symptom	Probable Cause	Documented Fix
Humidor humidity too low	Uncalibrated gauge reading low	Run a salt slurry test or use a commercial calibration kit
Humidor humidity too low	Cedar wood unseasoned or dried out	Re-season the empty box with high-RH packs or distilled water trays
Humidor humidity too low	Leaky lid seal or loose joint	Double humidity pack counts or inspect joints for warranty replacement
Humidor humidity too low	Undersized humidification device	Size packs or crystal jars to the box's rated maximum capacity
Humidor humidity too high	Humidifier overfilled or too large	Reduce water volume, restrict adjustable vents, or use dry cedar strips
Humidor humidity too high	Room overheating near heat source	Relocate humidor away from radiators, direct sunlight, and hot walls
Readings swing wildly	Temperature changes in the room	Keep the humidor below 72 degrees Fahrenheit, away from heat sources
Two gauges disagree	Different local microclimates or drift	Test both units together in an airtight container at 75 percent RH

A reading that sits stubbornly below your target range leaves tobacco vulnerable to drying out. If the reading stays low, work through calibration, the lid seal, and the wood, in that order.

Hygrometer Calibration and Testing

Hygrometers come in two main varieties: analog and digital. Tobacconist University (TU) notes that neither should be assumed accurate simply because it displays a number. Analog hygrometers work mechanically, and their parts can drift over time, requiring a check roughly every six months or whenever cigars do not feel right. Digital hygrometers come factory calibrated and often show better accuracy out of the box, but they can still drift.

To run a home calibration, mix about 1/2 cup of table salt with about 1/4 cup of water to make a wet slurry with undissolved salt visible. Seal the slurry with the gauge inside an airtight container or bag without letting them touch, and leave it at room temperature for about 24 hours. A saturated salt solution produces very close to 75 percent RH. If your gauge reads 72 percent in that environment, note that it runs 3 points low, meaning a future reading of 67 percent indicates 70 percent actual moisture. For non-adjustable units, you must apply this offset calculation every time you read the screen.

Commercial calibration packs offer an alternative to kitchen testing. Boveda disagrees with TU here: it says you cannot make an accurate salt test at home, because the RH a homemade mix produces depends on the salt-to-water ratio. The Boveda Hygrometer Calibration Kit is sealed in a leakproof membrane, and Boveda machine-checks each production run to confirm 75 percent RH. A test takes about 24 hours. For a fast functional check, TU describes wrapping a gauge in a damp towel that is not dripping for about 20 minutes. It should read near the top of its range, but TU says this does not replace a true calibration. Learn more about selecting reliable gauges in our guide to cigar hygrometers.

Testing and Correcting the Lid Seal

If your gauge is accurate but the moisture level remains low, the box may be leaking air. Northwoods Humidors outlines two practical tests for checking seal integrity. First, try the whoosh test by opening and closing the lid. You should feel a slight push of escaping air or hear a gentle whoosh sound. If you feel no air move and hear no whoosh, the seal may have gaps.

Second, perform the dollar-bill test. Place a bill across the lip of the box so half sits inside and half sits outside, close the lid, and pull gently. You should not be able to pull the bill out freely. If the bill slides out with little or no resistance, the seal is compromised.

When a seal fails, Northwoods Humidors identifies a manufacturer warranty claim as the preferred path. Northwoods also describes a DIY repair it does not recommend:

1. Remove the cigars and the humidifier.
2. Run a small bead of food-grade silicone into the gaps.
3. Let it dry with the box open for 72 hours.
4. Re-season the wood.

Boveda gives a simpler fix for a leaking seal: double the number of packs. Compare structural options in our roundup of the best cigar humidors.

Seasoning Dry Spanish Cedar

Unseasoned or dried-out wood behaves like a sponge. As Boveda explains, an unseasoned wooden humidor pulls moisture straight out of your cigars. Dry cedar absorbs ambient moisture slowly before it can support a stable internal climate. TU notes that seasoning can take several days or longer, and you should never add cigars immediately after the hygrometer hits your target number for the first time. Give the humidor time to stabilize, generally within 65 to 70 percent RH.

Never wipe distilled water directly onto the interior cedar planks. TU warns that putting liquid water directly on the wood can swell or warp the wood and stress the joints, lid and seal. For a standard 100-count humidor, Boveda notes the cedar requires approximately 100 grams of moisture to condition properly. Four Size 60 84 percent seasoning packs release roughly 35 grams each, raising the box to roughly 65 percent RH across 14 days. While seasoning at 84 percent RH, Boveda recommends storing your cigars separately in a sealed bag or airtight container with 69 percent packs, because 84 percent is too high for safe cigar storage.

Cigar Aficionado gives a revival method that keeps water off the wood:

1. Put a sponge in a container half-filled with distilled water inside the closed humidor for one day.
2. Replace it with a charged humidification device and keep the lid closed for three days.
3. Check that a digital hygrometer reads 65 to 72 percent RH before you load cigars.

Follow our complete step-by-step method in how to season a humidor.

Sizing Humidification Devices Correctly

A humidor not holding humidity may simply lack enough humidification surface area. Boveda sizes its packs based on the total rated cigar capacity of the humidor rather than how many cigars currently sit inside. For example, a 50-cigar box requires two Size 60 packs whether it holds 5 cigars or 35 cigars. For larger capacities, a 100-cigar humidor requires four Size 60 packs, a 200-cigar box requires eight packs, and a 400-cigar humidor requires sixteen packs. Alternatively, one large Size 320 pack handles a capacity of 25 to 125 cigars, while four Size 320 packs cover 350 to 400 cigars. For small travel containers, Boveda recommends one Size 8 pack for every 5 cigars of capacity.

Boveda clarifies that using additional or larger packets will never over-humidify your cigars. Size 60 packs hold relative humidity within 2 percent of their rating when you use the recommended number of packs. Drafty wood boxes or dry room air can pull the reading down. In a porous wooden humidor, Boveda says a 69 percent pack often reads 2 to 5 points lower. For a 69 percent target, Boveda suggests a 72 percent pack, and for a 72 percent target, a 75 percent pack. Boveda says to replace two-way packs about every three months. Do not mix RH levels in one humidor, and do not combine two-way packs with other humidification devices, because they work against each other. For more on pack ratings, consult our guide to Boveda cigar humidity packs.

If you use passive refillable systems, the fluid type and surface area dictate moisture output. Propylene glycol (PG) activation solution mixes distilled water with PG. Northwoods Humidors explains that PG absorbs excess humidity while helping maintain proper target moisture, recommending treatment every one to three months. Refill the device whenever the reading drops below 65 percent RH, and never use tap water, because chlorine and minerals compromise the humidifier and can add off flavors. The XIKAR Crystal 2 oz jar ships dry and is activated with PG solution or distilled water, according to Neptune Cigar's listing. It releases a constant 70 percent humidity for up to 75 cigars and lasts up to 90 days per fill. The XIKAR Crystal 50 gel absorbs 450 times its weight in fluid, and Neptune Cigar's listing says to recharge it when the crystals start to contract. Northwoods Humidors notes that if your device's evaporation surface is too small for the box, your cigars will end up dry. Compare devices in our guide to choosing a humidifier for a humidor.

Adding Dry Cigars Gradually

Introducing a dry box of cigars can cause a sudden, temporary drop in your readings. TU notes that cigars continuously absorb and release moisture, meaning newly added sticks draw humidity from the air and wood. Allow the cigars, cedar, and humidification devices time to equilibrate before you adjust your equipment. Boveda says never to put new cigars straight into a wood humidor. Bring them to your target RH first in a non-porous container, such as an acrylic humidor or a lidded plastic container, with two-way packs, then move them into the cedar box. If your sticks have dried out severely, review how to rehydrate dry cigars.

High humidity in a humidor traces to an overfilled or oversized humidifier, a box that runs too warm, or too few cigars in a large box. TU notes that over-humidified cigars can turn soft, draw uncomfortably tight, burn unevenly, require frequent relighting, and develop sour, acrid, or muted flavors.

Addressing Spikes and Avoiding Mold

A short spike above target, often from summer heat, is not a concern on its own. According to Humidor Discount, take action if RH settles above 75 percent for an extended period. Humidor Discount warns that allowing moisture to linger above 75 percent RH significantly raises the risk of tobacco bloom or harmful mold growth.

Cigar Aficionado notes that mold can also form if you fail to use distilled water inside your humidification units. If mold develops, TU advises discarding any visibly affected cigars rather than attempting to brush them off or dry them out. For cleaning Spanish cedar, TU suggests 70 percent isopropyl alcohol applied sparingly with a cloth, never poured on. Let the humidor dry and air out completely before you restock it. Northwoods Humidors disagrees with TU on cleaning. It calls alcohol and vinegar ineffective and says they may affect flavor. Its steps are to wipe the wood with water only, sand with 120-grit sandpaper, dry the box, re-season it, and recalibrate the hygrometer. To inspect your wrappers, consult our breakdown on cigar plume vs mold.

Safe Methods to Lower Humidity

Humidor Discount says to check the hygrometer calibration first, because analog units are very sensitive to vibration. If you filled the humidifier in the last seven days, it may be releasing too much moisture for the box. Humidor Discount suggests refilling with less water, switching to a smaller unit, or closing adjustable ventilation louvers. Moving cigars away from the immediate vicinity of the humidifier also prevents localized dampness.

Sources offer conflicting advice on airing out a damp box. Humidor Discount suggests leaving the humidor lid open for a few hours and repeating the process after a few days if high readings persist. Conversely, Cigar Aficionado warns against leaving the lid open, pointing out that humidity can swing wildly and moist cigars can quickly dry out. Instead, Cigar Aficionado recommends placing dry cedar strips across the bottom, middle, and top of the box to absorb excess ambient moisture gradually until the readings settle.

Northwoods Humidors notes that storing cigars too close to a large evaporation surface leaves them damp. Cigar Aficionado adds that a very large box holding few cigars can leave those cigars absorbing more than their share of humidity. It says overhumidification is especially common in summer and in humid climates. Maintain standard storage targets by referencing our cigar humidity guide.

Room Temperature and Environmental Swings

External temperature directly alters the relative humidity inside an enclosed humidor. TU states that small, gradual temperature shifts are normal, but rapid swings disrupt internal equilibrium. Keep humidors away from direct sunlight, heating ducts, radiators, and hot exterior walls. Northwoods Humidors warns that an overheated humidor experiences rising internal humidity alongside a higher risk of mold and tobacco beetles.

TU recommends keeping cigar storage temperatures below 72 degrees Fahrenheit whenever possible, noting that cigars store safely in the 60s or even the 50s as long as the relative humidity remains stable. Boveda says dry climates and high altitude make RH harder to hold in wood and glass-top humidors. In those conditions, it suggests switching to an airtight acrylic humidor or a humidor bag. Compare container formats in our review of electric vs regular cigar humidor designs.

When two gauges in the same box display conflicting readings, do not assume one is broken. TU explains that a hygrometer only measures the localized air pocket immediately surrounding its sensor. In a desktop humidor with a top-mounted humidifier, a gauge near the top may not represent conditions throughout the box. Airflow restrictions, how tightly cigars are packed, and proximity to the humidification device all create distinct microclimates.

To resolve the discrepancy, run a benchmark calibration test. Place both gauges side by side inside a sealed plastic container or calibration bag with a Boveda calibration kit or a saturated salt slurry for about 24 hours. If both read 75 percent, the gap between them in the humidor comes from real differences in airflow and placement. If one reads off, trust the one that read 75 percent, or correct the other by its offset each time you read it. Finally, TU emphasizes that there is no substitute for physically inspecting and touching your cigars, because the condition of the leaf matters more than any single number on a screen.

Once your gauges are calibrated, your seal is confirmed, and your wood is seasoned, record your hygrometer numbers regularly to catch seasonal shifts before your tobacco suffers. Northwoods Humidors suggests checking humidity every two weeks and recalibrating the hygrometer every few months. Track your humidity and temperature trends over time with our free Humidor Tracker.