Autumn sunset

Ok, here's my little bug-bear when it comes to the seasons.

People say that:
- Autumn is September, October ,November
- Winter is December, January, February
- Spring is March, April, May
- Summer is June, July, August.

Now, I'm Irish and was therefore taught Irish at school.
The Irish for September is Mean Fomhair and October is Deireadh Fomhair respectively meaning 'middle of autumn' and 'end of autumn'.

So, surely that means:
- Autumn is August, September, October
- Winter is November, December, January
- Spring is February, March, April
- Summer is May, June, July.

So, who's right? Have Irish kids been taught the wrong thing for generations or is the rest of the Northern Hemisphere in it's own timezone?!

Answers on a postcard please.....