"New York City has reached the 3% testing positivity 7-day average threshold," de Blasio wrote on Twitter. "Unfortunately, this means public school buildings will be closed as of tomorrow, Thursday Nov. 19, out an abundance of caution."
De Blasio added, "We must fight back the second wave of COVID-19."
Meanwhile, Sachem Central School District Board of Education will discuss on Wednesday evening how rising infection rates could affect instruction locally.
"We will be talking...about the NYS guidance around Yellow, Orange and Red zones and how New York State’s decision on schools in this region could impact us," Sachem Central School District Superintendent Christopher J. Pellettieri wrote in a letter. "Just so you are aware, we are not, at this time, planning any pre-emptive closing after the Thanksgiving break."