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Upright Bass Humidity Check

Type your city and this free tool shows the humidity where your upright bass lives, right now and for the next seven days, and tells you when the air’s dry enough to open a seam or crack the top. Got a hygrometer? Enter its reading and the tool judges that instead, because the number in your room matters more than the one outside.

The safe range, the danger line and every step it suggests come from bass shops, string shops and humidifier makers. They’re listed at the bottom of the page, along with where they disagree.

Free tool

Check the air your bass lives in

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A hygrometer reading from the room where the bass lives beats any forecast. No hygrometer? We’ll estimate the room from the outdoor air.

How the humidity check works

  1. Type your city, or tap Or use my location. The tool pulls the forecast for the next week from MET Norway, the Norwegian Meteorological Institute. Add the state or country after a comma if there’s more than one, like Portland, Oregon.
  2. Set your thermostat. Whenever it’s colder outside than that, the tool warms the outdoor air to your setting to estimate the room your bass lives in.
  3. Pick carved or plywood. Hybrids (carved top) count as carved, the way Gollihur Music groups them. Plywood basses get different advice, explained below.
  4. Enter your hygrometer reading if you have one. That’s the number the tool judges first.
  5. Read the gauge, the week and the steps. The week shows the day the room air leaves the safe range, so you can get the humidifier going before it happens.

Why the air indoors matters more than the forecast

Cold air doesn’t carry much water. When your furnace warms it up, the water in it stays the same but the temperature climbs, so the relative humidity falls. Run the National Weather Service’s vapor pressure formulas and a damp winter day turns into desert air indoors: 80% humidity at 30°F works out to about 19% once it’s warmed to 68°F.

Bass people see the same thing at home. Bob, who started Gollihur Music, a bass gear shop in southern New Jersey, writes that when his forced-air heat comes on, “Indoor humidity drops like a rock.” Shar Music says indoor heating in fall and winter brings “rapid humidity drops.” Johnson String Instrument says cold weather and dry indoor heating “create some of the most challenging conditions for string instruments.”

That’s why a hygrometer in the room where the bass is stored beats any forecast. Upton Bass, which builds basses in Mystic, Connecticut, puts it plainly: “If you own a bass, you need to own a humidity monitor.” Shar says a wall-mounted one in the same room is the easiest way to measure, and that smaller ones may not be as accurate.

What humidity is safe for an upright bass?

Most of the shops and makers we checked give the same range: 40 to 60% relative humidity. That’s Johnson String Instrument, Shar Music and Boveda. D’Addario aims tighter: 40 to 50% in its guitar care guide and 45 to 50% for its Humidipak packs. Johnson String adds a temperature: 60 to 70°F.

Below 40% is where trouble starts. Shar says the risk of damage “increases significantly” under 40%, and Johnson String lists what you get when the air drops that low: “lowered string heights, a change in tone, open seams, and cracking.”

Not every source sets the floor that high. Gollihur Music’s Bob runs his humidifiers at “between 30% and 40%.” An older Shar guide from 2011 matched the indoor target to the weather: about 30% indoors when it’s 20% or drier outside, 30 to 40% when it’s 30 to 40% outside, and 40 to 50% when it’s 40 to 60% outside.

So the tool uses the cautious common range:

  • 40 to 60%: safe. The range Johnson String, Shar and Boveda give.
  • 30 to 40%: too dry. Under the 40% floor most sources give. Not an emergency by Gollihur’s numbers, but it’s time to humidify.
  • Under 30%: dangerously dry. Below every range we found, including Gollihur’s and Shar’s 2011 table. This is the level that triggers the dry-air email.
  • Over 60%: too humid. Johnson String says high humidity “may soften wood and weaken glue joints,” and Gollihur says very high heat and humidity can make seams separate.

Fast swings are the other danger. Gollihur says extreme conditions, “and especially, rapid CHANGES between conditions,” aren’t good for any instrument. None of the sources puts a number on how fast is too fast, so the tool doesn’t invent one. It flags the day the forecast moves your room out of the safe range.

What dry air does to a bass

Gollihur describes it on his own carved bass: the heat comes on, moisture leaves the wood, and the top or back shrinks, which “puts pressure on the whole structure.” If the seams are glued right, the hide glue lets go first, “sort of an organic safety valve,” and that fix is “usually an inexpensive one.” If not, the wood cracks, and that repair can cost “potentially very big bucks.”

Johnson String says the same about seams: they’re “designed to act as a safety release,” so the hide glue separates before the wood itself cracks. Cracks, when they come, tend to start near stress points like the saddle or the soundpost area, and Johnson String notes that the larger plates of a cello make it more vulnerable. Gollihur calls a carved bass’s top and back “massive.”

Before anything opens, you’ll usually feel it in the setup. Upton Bass points out that the average 3/4 bass has a string length of 41.5 inches, so when the humidity changes “and the wood of your double bass changes just the slightest bit, that small wood movement can result in a virtually unplayable bass.” That’s why it recommends bridge height adjusters for players whose seasons bring different humidity levels.

Carved, hybrid or plywood?

Gollihur’s answer to “do you need to humidify?” depends on the bass. “If you have a laminated (plywood) bass, no. Carved or hybrid (carved top), yes, or at least, maybe.” Laminated basses “were developed for this very reason”: the layered wood doesn’t move with the weather enough to crack. He still says extremes and rapid changes aren’t good for any instrument, and that very dry weather could affect the solid wood end block, “though it doesn’t happen often.”

Room humidifier, Dampit or humidity packs?

  • A room humidifier is what Gollihur recommends for a carved or hybrid bass: a household unit, ideally with a built-in humidistat and a digital readout so it holds the number you set. Shar’s 2011 guide agrees that humidifying the room the instrument lives in most of the time is the most advisable approach.
  • A Dampit-style tube hangs through the f-hole. Gollihur says it’s only worth using when the bass is inside its bag or case. Out in the open, the moisture just humidifies the room. Soak it, squeeze out the excess and wipe it off, and don’t overdo it: Gollihur says luthiers end up cleaning mold out of basses that were kept too damp.
  • Two-way humidity packs like D’Addario’s Humidipak and Boveda add or absorb moisture to hold a set level inside a closed case: 45 to 50% for Humidipak, 49% for Boveda’s standard packs. D’Addario says the packs are best used in a sealed case.

Whatever you use, keep the bass away from radiators, heating vents and drafty windows. Shar suggests an interior wall or an insulated bedroom or closet, and never an attic or a basement.

Go deeper

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An 11-exercise daily warmup for upright bass with Simandl-correct fingerings.

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Upright bass humidity FAQ

What humidity should I keep my upright bass at?

Between 40 and 60% relative humidity, the range Johnson String Instrument, Shar Music and Boveda give. D’Addario aims for 45 to 50%. Gollihur Music’s Bob keeps his room at 30 to 40% in winter, so sources do differ on the floor.

How dry is too dry for an upright bass?

Shar says the risk of damage increases significantly below 40%. Under 30% is below every range we found, which is why the tool calls it dangerously dry.

Why is my house so much drier than the weather report?

Heating. Warming cold air doesn’t add water, so its relative humidity falls. By the National Weather Service’s formulas, 80% humidity at 30°F is about 19% at 68°F.

Does a plywood bass need a humidifier?

Gollihur Music says no: laminated basses were developed so the plates wouldn’t move with the weather. Extremes and fast changes still aren’t good for any bass.

Does a Dampit work in an upright bass?

Only when the bass is zipped into its bag or case. Gollihur says that out in an open room the moisture just drifts into the room, and Shar says an in-case humidifier stops helping as soon as the case is opened.

Keep going

Sources