My Hang, try not to worry too much, do you know when she will be getting the surgery?
For me, the first week after the operation was the hardest, but you are put on enough pain medication so it isn't too bad. The nurses will look after your daughter very well and make her as comfortable as possible. You also have medication for when you are at home, and even though it is still sore for a little while, it gets better and better every single day.
I am in no pain at all now, it feels great

and i haven't noticed any change in my back according to the weather, i don't think it effects me at all.
best wishes to your daughter