This one really comes down to whether you live in the southern or northern hemisphere because, unsurprisingly, it’s all about weather. If you live in the southern hemisphere, then the chances are that you start your school year in January or February. In the USA, like many other countries in the northern hemisphere, you would start the school year in September.
Each hemisphere thinks the other one is weird, mainly because once you get used to doing something one way, the possibility of changing feels far too weird. For many farming communities, September was a sensible time to come back to school, once the harvest had been brought in.