Estyn said they fall short in about half of the county’s primary schools and in all three of the secondary schools inspected since 2017.
They also found shortcomings in the quality of teaching, and behaviour by secondary pupils was poor with a high level of short-term exclusions.
Pembrokeshire council said it had made “strong progress”.
But it recognised change had been too inconsistent and slow since its education services were put into special measures eight years ago.
This is done when inspectors believe there is a failure to supply an acceptable level of schooling and they appear to lack the leadership capacity to improve.
Pembrokeshire was taken out of special measures two years later but Estyn has found pupils’ standards were “too variable”.
The inspectors praised “strong” achievements by pupils studying Welsh as a first language, but said they were concerned by progress among Welsh second language students in half the primaries and all secondary schools.
“Shortcomings in the quality of teaching, including low expectations and a lack of progressive and planned opportunities to develop literacy, numeracy and Welsh second language across the curriculum limit the progress pupils make,” the report said.
It added the number of pupils excluded for five days or less was “notably higher” than the national average in secondary schools.
The inspectors praised the “valuable” work of the behaviour support team in starting to improve pupil behaviour, particularly in primaries.
But added: “However, in secondary schools, particularly in a very few secondary schools, pupils’ behaviour is not good enough. Overall, the number of fixed-term exclusions is markedly higher than in secondary schools across Wales.”
‘Significant concern’ over education services
The council’s plans to reorganise education were praised for their “ambitious vision” and “clear strategy”, but inspectors found flaws in a small number of areas with improvement proposals “not sufficiently sharp”.
It said the county’s education services “are causing significant concern and require follow-up activity”.
It pledged to work with schools to ensure improvements are made.
Guy Woodham, the council’s cabinet member for education and lifelong learning, said: “While there is recognition by Estyn of the progress made since 2012, the pace of change across the local authority has been inconsistent and has not taken place fast enough.
“In going forward it is important that all those involved in education now focus on urgently raising performance outcomes and improving the quality of teaching across all our schools.
“Our ambition remains the same that every learner achieves more than they thought possible.”