Temperature. Humidity and Your Acoustic Guitar: What You Need to Know

By Jennifer Hughes
March 5, 2019

Acoustic guitars, no matter the size and shape, are affected by humidity and temperature. Whether it’s an inexpensive starter guitar, a mid-range acoustic guitar below $1500 or a high-end professional model, it can get damaged when subjected to low or high humidity and extreme changes in temperature.

How Humidity and Temperature Affect Acoustic Guitars
Humidity refers to the amount of water vapor or moisture in the air. A low humidity means the air is drier, while a high humidity means there’s a lot of moisture in the air. Relative humidity is the amount of moisture in your surroundings relative to the amount of moisture the air can hold before the saturation point is reached. As the temperature increases, so does the air’s ability to hold additional water.

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Changes in relative humidity, along with changes in temperature, cause damage to an acoustic guitar. The wood on acoustic guitars reacts to humidity in the same way that other types of wood do. It swells when it’s too moist and it shrinks when it’s too dry. When a guitar is exposed to dry conditions for a long period of time, it loses its stored moisture and the wood shrinks.

This may result in cracking, the frets protruding and the action getting low with lots of fret buzz. A too-dry acoustic guitar that has shrunk puts a lot of strain on the top, compromising the structural integrity, play-ability and sound of a guitar.
If a guitar is exposed to excessive humidity, the seams may separate, the action may become unplayable and the bridge may come loose. These kinds of damage are why it’s important to make sure you store your guitar in a place with ideal levels of humidity.

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How to Keep Your Acoustic Guitar in Good Playing Condition
The ideal humidity range for all acoustic guitars is 45 to 55 percent. Here are some tips to follow to make sure you protect your guitar from the ravages of extreme humidity and temperature changes:

• Monitor the humidity level of the place where you store your guitar. Use a digital hygrometer for greater accuracy. A low humidity level means you need to use a humidifier; a high humidity levels means you should use a dehumidifier. Keep the hygrometer in the guitar case with your instrument.
• Store your guitar in its case (a hard case is recommended) when not in use, especially if you like in an area with low humidity.
• Use a humidifier. There are specially designed humidifiers for guitars that provide two-way humidity control. These humidifiers are able to absorb or release moisture so that humidity levels are kept at within the ideal range.
• Be aware of the warning signs of a dehydrated guitar. Check your guitar for any signs that indicate it’s dry. These include sharp or protruding fret ends due to a shrunk fingerboard, cracks on the wood, a lowered action and string buzz. If you observe these signs, proper humidification is in order.

Final tip: If you are unsure of the extent of the humidity and temperature damage to your guitar and what you need to do to fix it, don’t hesitate to bring it to a guitar technician right away. There’s no quick fix or restoration process for acoustic guitars, so it’s best to leave the repairs to the pros. 

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