Fcps calendar

Can someone explain this to me? I’m not originally from Virginia so I’m having trouble understanding how some schools in FCPS are both city of fairfax schools and FCPS schools - I get location obviously but how do little things like county wide decisions work? Do schools like Katherine Johnson middle school, Fairfax High School etc follow a different calendaregulations etc?

Monday, March 2 - 5:30 p.m. - Dear Parents and Guardians,
At this time, we anticipate an on-time start for school tomorrow as we strive to resume our regular academic calendar. However, the National Weather Service is forecasting the possibility of freezing rain or sleet for tomorrow and this could result in an early dismissal of classes or the cancellation of after school and/or evening activities in FCPS schools or on school grounds. Please monitor the FCPS website and Facebook and Twitter accounts, plus local media, and expect to receive a Keep in Touch message should we need to dismiss early or cancel after-school events. Thank you for working with us as we continue to cope with this difficult winter weather.
Karen K. Garza, Ph.D.
Superintendent of Schools
My interpretation: TL;DR - Might get an early release tomorrow, depending on temperatures. If the rain freezes, we'll probably try and get everyone home asap. If not, you're SOL and gotta go. And most likely no late runs or after school activities. Will update if/when I can, as soon as I hear.