Barnsley Council has become the first in England to cut the school summer holidays to under five weeks.
The council has published the term dates for the 2017-18 academic year, which include a shortened summer break, on its website.
Children will enjoy an extra week off in October instead.
But some teachers in the area are reportedly unhappy with the change.
Horizon community college headteacher Nick Bowen said that the council should reconsider as there had been little consultation with school leaders.
He said it would also affect schools' ability to recruit high-quality staff as teachers want and need a chance to 'recharge their batteries'.
"There is also the fact that most of the academies in the area probably won't come on board with it so everyone will have different holidays," he added.
"And it will be a disaster in terms of attendance because parents who have multiple children will have to take other siblings out of school if the holidays don't match."
Coun Tim Cheetham, of Barnsley Council, said: "The decision to alter the borough's term times and holiday dates is based on sound research evidence that shows the maximum length of the summer break should be no more than five weeks for the best educational outcomes."