Parmandur
Book-Friend, he/him
WotC has released a book in late Septwmber every year since 2014, and each time they have advertised it as a Summer book.Technically, yes; but most people IME generally tend to see "fall" as beginning the day after Labour Day, when school starts and things move back into the not-summer routine.
Same way many tend to see "winter" as beginning right after US Thanksgiving, even though the solstice is roughly 4 weeks later.