More than 8,000 pupils are missing the start of the new term because their schools were hit by the summer floods, the Government said.
The vast majority of the 857 schools affected by the severe weather in June and July are opening for classes on time.
But there are 8,055 pupils in 21 of the worst-hit schools which have not yet reopened, the Department for Children, Schools and Families said.
Officials said all the schools are expected to be open again by next week and there are plans to make sure children make up any time they have lost.
Schools minister Jim Knight praised all the staff who worked to make sure the children's education would not suffer.
"It is a great achievement that after severe flooding in June and July, almost all of the 857 affected schools are reopening on the first day of term," he said.
"This is testament to the dedication of staff who have put the welfare of young people first - despite many having their own homes flooded."
In all, more than 360,000 pupils were in schools which were damaged in some way by the unprecedented weather.
Mr Knight said extra money would be made available to local authorities which need more help, on top of the £14 million already pledged.
Gloucestershire is receiving an extra £350,000 to help with the loss of water supplies, which caused severe disruption to services for children and families, he said.
