Here in Central Pa. USA. We've having April like weather. My guitar tunings on all my guitars are getting "Sharp" just like they seem to do every spring but tonight, St Patty's day, this drunk Irish American, (who didn't have a gig tonight), decided to walk around my sound room with a "guitar tuner" and test a bunch of guitars.
Basically most all of my acoustics were between 30 and 60 cents higher than when they were tuned about a month ago which was at around 40% humidity. Tonight the humidity is 60%.
Humidity affects pianos the same way. The sounding board shrinks with low humidity (decreasing tension on the strings) causing a piano to go flat, and swells when the humidity increases (increasing tension on the strings) causing the pitch to go sharp.
Hmmm. I did a "polish & tune" run on all the acoustic instruments at the Emporium the other day, and they were ALL down at least a half-step, one was down a whole-step. I did notice the humidifiers were shut down until we purchase more humidifier bacteriostat, so the change must have caused it. Interesting.
