If there is a holiday, then we will know because the Weekly Shonen Jump will give us what is known as a 'Double Issue'. This does not mean we will get two chapters for one week. In fact, it means the exact opposite: we get one chapter over a two week time span.
Outlined below are the dates of each holiday break that the Weekly Shonen Jump observes, along with the issue number for the corresponding Double Issue:
Issue #04-05 (3rd week of December) --> No WSJ in last week of December (End of Year)
Issue #06-07 (first week of January) --> No WSJ in 2nd week of January (New Year)
Issue #22-23 (last week of April) --> No WSJ in 1st week of May (Golden Week)
Issue #36-37 or #37-38 (first week of August) --> No WSJ in 2nd week of August (Obon week)
So based on that, it is safe to assume that we will have a chapter tomorrow. The next Double Issue (i.e. holiday break) for WSJ will be in the last week in December.
Bear in mind that WSJ's holiday break (Double Issue) is different from an individual manga taking a break. For example, Kishimoto may take a break and there will be no Naruto chapter for a week. However, we will still get One Piece and Bleach because WSJ itself is not on break. You cannot predict when the author decides to take a break, you can only know at the end of the chapter that precedes the break.
I hope this general information cleared some things up for you guys. In the meantime, as we wait for tomorrow's new chapter, you can read the latest chapter (654) in full color by clicking on my sig.