[This article is about weather patterns and climate in the Flagstaff region of northern Arizona. It was written in 2021, and a lot of the information is still relevant to understanding the humidity patterns in this area.]
Can you over-humidify an acoustic guitar?
I observe patterns with our workflow and the repair demand related to the weather around here, specifically the humidity levels.
This area is known as a high desert, where low humidity is a big concern for musicians with acoustic instruments. Obviously, dryness can cause all sorts of problems for instruments made of wood, cracks, playability issues and other things. It’s a common topic I bring up with customers. We’ve discussed these issues in other articles here and here.
But today I want to talk about something that seems new, or at least rare. I’ve been monitoring outside and indoor humidity on a nearly daily basis for the last 15 years in this area, and I’ve never seen it before. This level of consistent moisture and sustained humidity is unprecedented. [UPDATE 2022: This has remained true this year again!]
The Shock is Coming
When it gets dry again be careful! Your guitar is going to experience a shock. I’ll tell you how to help prevent it later. But here’s why it matters.
We’ve been sustaining a solid 50%-60% humidity here for weeks now. Our monsoon rain season has caused a “500-year flooding event” as seen on the news this summer. (2021)
I remember during past monsoon rains I would put a hygrometer outside under an awning. It would max out at around 60%… during the rainstorm! Then the monsoon would stop, and as the sun came out again it would go back down to 30% or lower.
Not this year! Even on days when it hasn’t been raining, we’ve seen regular 60% humidity. This is historically anomalous and it will be hard acoustic guitars when the weather dries out again.
Historical Averages
I want folks to know there is a difference between the readings at our local airport (where the NOAA data comes from) compared to the actual humidity in town. But take a look at these month-to-month humidity averages.
Flagstaff, AZ, RH monthly averages. [source: flagstaff.climatemps.com/humidity.php]Don’t be fooled. These averages skew upward in practical terms for a few reasons. During the summer months you can have four days of 10%-20% humidity and then a couple days of rain and the average comes out to 39% for the week. In this instance your guitar was in dangerous conditions for the majority of days, then it had a couple days to start normalizing before the routine started again. These cycles can be detrimental over time. Consistency is the key to a happy guitar.
During winter months with the snow fall, cold temperatures and evaporation cause higher readings and averages outside. But the heater inside your home is likely drying out the air to a dangerous level for your guitar.
How to Prevent The Coming Shock
The main thing to know is that while your guitar is happy right now, if not a little too happy with so much humidity, watch out for the crash! After the monsoon season finishes up and our humidity drops back down to 20% – 30%, your guitar is going to experience a shock.
Here’s what you can do…
- Pay Attention to the humidity on the weather report and in your home.
- Pay Attention to how your guitar is playing. Has something changed lately?
- Learn the symptoms of a dried out guitar
- Buy a hygrometer, monitor the humidity near your instrument
- Get a humidifier, keep your guitar at approx. 40% RH
- Use a hard case. Any case is better than none.
So, can you over-humidify a guitar?
Not at 50% – 60% RH, or even a little higher. While that’s a bit too high, it’s the gradient and rapid changes in humidity that will be a problem. A detrimental level of humidity for a guitar is more around +65% for sustained periods. Almost every acoustic guitar is happiest and sounds best at 45% RH (+/- 5%).
