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.