Last year we went through the same situation after Irene and October snow storm.
They 'proposed' cancelling the winter break in order to make up time. We had lost about a week each storm.
The teachers indicated that they had planned vacations and the school district caved, despite meetings, despite angry parents, despite letter to Board of Education. The school district claimed it would not have enough substitute teachers to cover all the teachers who would be out, they needed over 64 substitutes. So no cancelled winter break.
As much as I never wish to take my children out from school for a vacation, after that example was set by teachers and Board of Education, I would not cancel anything.