Blessed rain..

Given that people's moods are subject to variability perhaps even more than the piano, it is possible that with humidity the soundboard reacts by swelling and that there is a slight increase in tone and tension on the bridge. But the piano does not transform; rather, the humidity could be absorbed by the felts, resulting in a modification of the timbre. Air humidity also makes the medium of sound transmission different, leading to changes at the impedance level. Variability is an indicator of instability; whether this is perceived positively or negatively is never a good sign, regardless of whether it concerns the piano, the pianist, or the environment. Open the windows and avoid condensation.

Giovanni, in a few words, provides a perfect analysis. It depends on us, on the more or less dense medium (% relative humidity in the air), and on the instrument. Lastly, the absorption of moisture by the hammers (which tends to soften the sound, making it more opaque). Condensation should be avoided. Don't you think, Giovanni, that that very last "lick" of light sealant that manufacturers apply after tuning tends to "waterproof" the hammers a bit against strong humidity variations? What is your opinion?

Good morning Paolo, sometimes I miss the hammers with the grey reinforcement, which are no longer produced, precisely because I find they were more stable even if it wasn't a deep impregnation and in the opinion of many technicians it was useless..

In my opinion, hammer stability depends as much on the type of felt, its compression, and above all on how it was prepared. A correct choice of the same can also lead to more rational wear.

Wise words, Giovanni!!!!