I'll second those boxes as being good - we used two of them at Christmas time last year to hold the dimmers for the (computer controlled) lights.
We had one tied up in a tree, and another buried in the ground; each with about 10 or so wires going into them. After being out in the weather for over a month, they were as good as the day we sealed them up. (And nothing went wrong with our electronics either - all set for this year )

We stuck the cables in through cable glands - which, if you're going to use this sort of box, you probably ought to do - to keep the dust & water-proof rating up.
Putting the seal on the lid properly is a little tricky at first, and takes a bit of patience and practice, but worth doing.