I weigh daily too. I know it's probably not the best idea, but in this early stage of trying to lose a lot of weight, I feel better doing this daily. It's a bit disappointing on the "up" days (I luckily haven't had many so far), but I can take comfort in telling myself that it's probably just water and it makes me more careful of what I am eating and doing.
However... on Sunday morning, I weighed in at 87.2kg... v. exciting, but on Monday, it was 90kg. This morning, 88kg. So, who knows?
Obviously I didn't gain and lose 2 kg overnight, but it seemed a lot to be accounted for by "water". I always weigh first thing in the morning and always in only knickers, so it may be just one of those things. Luckily, the general movement has been downwards.
Good luck and don't be put off by a few bumps along the road!