In the winter, I hear talk about schools cancelling classes because of snow.
One part of that discussion is that school officials are afraid of liability. In Virginia, the liability of school employees and school boards for simple negligence is limited by sovereign immunity and the school bus insurance statute, Va. Code 22.1-194, as Judge Wilson held in this opinion granting a motion to dismiss claims against individuals related a school bus accident in Botetourt County.
Another part of the discussion is what is the effect of school days on learning. The answer according to this article is that school days cause lower test scores.