Most guitars are effected by weather ( humidity, hot and cold temperatures), age, abuse and changing of string gauge and/or tuning. The weather will always effect a wooden instrument. Humidity or the lack of humidity will expand or contract tops, backs, fretboards and necks. All woods “breathe” and “flex” due to its moisture content. That’s way it is very important to humidify you instrument during the winter, especially if you own a high end, single-ply top acoustic guitar.
Weather is more forgiving to electric guitars than acoustics. A lot of the mass produced acoustic guitars manufactured today may take several years for the wood to settle and then stabilize ( sometimes for the better, sometimes for the worse). I get a lot of calls from players that say their guitars, after restringing it does not play the way it use to. Especially if the guitar has a floating bridge (floyd rose). The main reason is because they’ve change the gauge of strings they’re using. Going from lighter or to heavier string will change the tension on the neck.
Lighter string will allow the neck to pull back due to the lack of tension. As heavier string will pull on the neck due to the addition tension on the neck. The same is true with the guitars tuning. A guitar that I set up with 10's and standard tuning will not play properly if you put a set of 9's and detuned a whole step down. A guitar should be set up with the correct gauge of strings that suits your style of playing and than the proper tuning. Most guitar can handle a standard tuning with a dropped 6 th string.
