Back to school time is called "la rentrée" in France, and it's quite an event. Since much of the country is on vacation for a large part of August, it's also "back to work" or "back to the routine" time even for those who work.
Noah is going into 5e this year (7th grade), and Benjamin is going into 3e (9th grade). They will be in the same school, since middle schools covers 6th through 9th grade, then high school is 10th to 12th.
As soon as the calendar changed over to September, the temperatures dropped quite a bit, hence the jackets despite hitting the upper 80s last week!