California schools will be unable to reopen this year given current safety concerns and ongoing social distancing, the state superintendent told county officials Tuesday.

The letter, obtained by The Chronicle, was not a directive, but rather an acknowledgment that the still growing coronavirus crisis means schools should stay shuttered.

While classrooms should remain closed, education will continue, Superintendent of Public Instruction Tony Thurmond said.

“Due to the current safety concerns and needs for ongoing social distancing it currently appears that our students will not be able to return to school campuses before the end of the school year,” Thurmond said. “This is in no way to suggest that school is over for the year, but rather we should put all efforts into strengthening our delivery of education through distance learning.”

The memo was the guidance local districts had been waiting for to make the hard call to close schools for the year, education officials said.

“That provides a little more clarity for school leaders,” said Troy Flint, spokesman for the California School Boards Association. “I think a lot of school districts and certain county superintendents have been leaning in this direction, but have been waiting on something more definitive from the state to give them security in making this decision.”

Flint said he expects local school boards to begin making announcements of school-year closures based on Thurmond’s letter.

Ending speculation will allow districts to focus on distance learning, distributing school meals and providing other support without having to worry about whether schools will resume at an uncertain date, Flint said.

While Thurmond’s memo wasn’t a mandate, it was a call to action, for district’s to plan to do distance learning the rest of the year, said Alameda County Superintendent Karen Monroe.

“Every week is a new set of realities,” she said. “Once you say that (closing) is for sure, you better be able to say what is happening.”

Earlier this month, district officials across the Bay Area closed schools to combat the coronvirus, with most expecting to reopen in early April. Two weeks later, most extended that to May 4. Thurmond's guidance effectively gives districts the backing to make the decision to end speculation or hope that schools will reopen.

District officials in recent days said there was a sense that a year-ending closure was inevitable and they were hoping the state would make the call sooner rather than later.

“I think our leadership team would be thankful for that guidance,” said San Francisco school board President Mark Sanchez earlier Tuesday.

For the moment, however, San Francisco and many other districts are still officially scheduled to reopen May 4.

“The state superintendent did suggest that schools may stay closed for the rest of the year but the state has not issued a directive,” said San Francisco district spokeswoman Gentle Blythe. “SFUSD’s superintendent continues to work with other superintendents, the SF Board of Education and health officials to monitor the situation and will update families and staff if the closure timeline.”

It will still be up to each district to officially announce the decision to not reopen, but Thurmond’s letter offers a statewide perspective and backing for what is already an unprecedented shutdown of state schools.

“We know that we are dealing with a never seen before health crisis that challenges us in many ways,” Thurmond said. “But we also believe that as it relates to educating California students we must rise to meet that challenge, that we are stronger together, and that if we work together we can do more together for all of our students.”

Jill Tucker is a San Francisco Chronicle staff writer. Email: jtucker@sfchronicle.com Twitter: @jilltucker