Of the 43 schools in the area, Ofsted rates four as inadequate, its lowest mark, while six require improvement, as of 30 September.
Its latest figures list 12 as outstanding and 21 as good.
The regulator visits all new schools, including academies, within three years of opening.
Inspectors judge them on categories including the quality of teaching, personal development and welfare, the effectiveness of the leadership and pupils’ achievement.
Schools requiring improvement will be inspected again within 30 months, while those rated inadequate now face mandatory conversion into academies, funded directly by central government.
In North Yorkshire, there are 367 schools registered with Ofsted including primaries, 18 of which are rated inadequate while 39 require improvement – meaning 16% overall are below standard.
This is, though, slightly below the 19% average for Yorkshire and the Humber.
Across England, 20% of all schools were classed as outstanding, 66% good, 10% requires improvement and 4% inadequate.
But with more than 1,000 “outstanding” state schools going without an inspection in a decade, the National Education Union warned this did not accurately reflect the quality of education they offer.
Dr Mary Bousted, the union’s joint general secretary, said: “The fact that some schools haven’t been inspected for over 10 years demonstrates that the information Ofsted provides is misleading at best and may be downright wrong.”
The Department for Education recently announced it will consult on plans to remove the exemption for outstanding schools, a move Ofsted says it welcomes.
A DfE spokeswoman added: “This Government is committed to providing world-class education for all students.
“Teachers and school leaders are helping to drive up standards right across the country, with 85% of children now in good or outstanding schools compared to just 66% in 2010.”