Bus travellers in County Durham and Teesside are being urged to make alternative arrangements on Monday when drivers take strike action.
It is the second 24-hour stoppage by the members of the Transport & General Workers Union, in an ongoing dispute with Arriva about pay.
Workers had been balloted and turned down a revised offer. It follows their rejection of an earlier pay deal.
The drivers want parity with colleagues in Northumberland and Tyneside.
Local councils are advising parents that pupils who normally travel to and from school on Arriva buses service will be affected.
A spokesman for Durham County Council said: "We have alerted all of our schools to the impact this could have on attendance.
"Pupils who would normally travel on Arriva bus services to and from school have been advised to make their parents aware that, where necessary, they will need to make alternative travel arrangements on the day.
"Although exams are over, it is still, of course important that children and students attend school."