How cold is too cold to move a piano?

Question

I'm having a piano moved by professionals to my house tomorrow morning when its supposed to be between 40-45 degrees F and 65% humidity. I've asked them to cover it during the move. It should take less than an hour to move it from the store to my house, but I'm still wondering if there are definitive thresholds of temperature/humidity/dewpoint and time at which point you should say "don't move it". Should I leave it covered for a period of time after the move?

Update 2015: For the sake of future visitors. The piano was moved when the temperature was 50 F and in less than an hour. It was wrapped up in the truck and unwrapped before taking it out of the truck. When it arrived I used a IR thermometer on it and it registered 72 inside the casing. All seems well. And yes the movers were insured and experienced with moving pianos.

Update 2016: Still doing fine.

Answer 1

My personal experience is with a violin, not a piano. However, since both instruments are made of wood and metal strings, there are some parallels, so my answer should still be useful.

With a wooden instrument, cold alone will not cause damage. It may cause the piano to go out of tune while the temperature is different, and it may not completely recover without being retuned even after it warms up again. But the materials used in making the instrument (wood and metal) are not subject to actual damage just from being chilled. In a violin, a change in humidity can damage the instrument, but a piano is significantly sturdier and made of thicker wood, so I’d expect that would only cause tuning issues as well.

If the change is sudden, from freezing cold to room temperature, the finish on a violin can crack. From 50 degrees to room temperature is not enough to cause problems. I’d assume the same could happen on a piano. But if you give the instrument time to adjust slowly, you can avoid this issue. Leaving my violin in its case to adjust for 10 minutes indoors is sufficient even if it’s been in weather well below freezing for an hour. A piano would be harder to insulate well, but experienced piano movers could probably address this concern more specifically.

In short, at 50 F, the temperature is not going to cause any problems moving the piano. With the violin, I only begin to be concerned about temperature at below 30F, or above 110F, such as a hot car in the summer. For a violin, I just leave it in its case. For a piano in these conditions, I’d suggest talking to expert movers, or a piano repair specialist. They’ve probably got the most experience.

Answer 2

Having moved my pianos several times, I wouldn't worry about it at all if it's above freezing. The more concerning issue would the speed at which the piano is subject to drastic changes in humidity and temperature. If the inside of the building is steamy and warm and it's cold outside, then I'd open the door and windows ahead of time to let the piano acclimate and reduce the shock.