Education Minister Jean-Michel Blanquer said that all children would have to go back to school unless they had a good reason, and parents should not be afraid.
France already opened almost all schools gradually in the last weeks of term before the summer, with authorities anxious for children to make up ground lost during a virus lockdown from mid-March to mid-May.
The country was one of the hardest-hit in Europe by the coronavirus epidemic, with more than 30,000 deaths.
Infections have been rising rapidly again in recent weeks, at more than 5,000 daily for most of the last week compared with under 1,000 daily for the first three weeks of July.
Blanquer said all schools were nevertheless ready to reopen, but his ministry had plans for moving back to distance learning if local lockdowns have to be reimposed in the worst-hit areas.
President Emmanuel Macron tweeted encouragement: “Education is an opportunity, it brings us together,” he wrote.
“This new term has many challenges, but at last we are all back together again!”
At least some children were equally enthusiastic, with three siblings from Paris telling newspaper Le Parisien that spending lockdown and the following months by the seaside with only online classes, seeing nobody but their parents, had been very long.
“It’s been six months since we saw our friends!”, one of them, named Mathieu, said.