I would like to add to George Imirie's observation that honey can absorb moisture from the air after being extracted while sitting in an open container.

Two years ago I removed over 95 % capped honey from my two hives a week before I was ready to extract.  I did this so I could get my Apistan on in late August as was being advised by Dr. Hoopingarner (at nearby Michigan State University) and others at the time.  The week I left the supers sitting outside, well sealed from the bees and yellowjackets but  not the night air, the humidity was very high and reached 100% several nights as evidenced by heavy dew and fog.  When I got around to extracting, I noticed immediately that my honey was very thin.  I was baffled because I had thought I was safe in extracting supers that were nearly 100% capped.  I sent a sample in to Dr. Hoopingarner who kindly used his refractometer to measure moisture content and informed me that it was (as I remember now) just under 21%  moisuture content.  I didn't have "dry" honey to mix it with so could not bottle and sell it retail.  I kept it frozen to keep it from fermenting until I sold it to a large packer in bulk (yes, I informed them of it's moisture content) who was able to mix it with dryer honey for bottling.

The lessons for me were:
1)  Honey does indeed absorb moisture from the air readily (I knew that)
2)  Cappings are not a seal against that absorbtion taking place (I didn't know that)
3)  If extraction must be delayed, keep the supers in as dry of an environment as possible. (I now put a light bulb under my stack of supers, inside, if I need to delay)

Alden Leatherman