The school system is adding the extra days to accommodate another expectedly harsh winter after the polar vortex that afflicted last winter, he said.
"If we use more than that, we have other options," Guthrie said.
The calendar will go to public comment before the school board approves it.
The school board might also be losing some local control over the calendar in the coming years, as Maryland legislatures have formed a committee to study the feasibility of mandating the school year start after Labor Day, Guthrie said.
He said it is unclear if the mandated start date will begin in the 2015-2016 school year or 2016-2017.