Some say 2, some say 3 or more.
It can be a little confusing for some punters.
I personally say there is 2.
Low
May - October
High
November – April
Give or take a week here or there.
Most of the hotel rates schedules will highlight the season just by the $ being charged.
Over here in Aust, costs skyrocket with Easter, Christmas & New Year and to a lesser extent during the School Holiday Breaks (different in each state for public and private schools but give or take a week they are pretty close).
My main trips away O/S that I try to plan tend to be Sept/Oct – Weather, Rates etc are just on the turn from Down to Up and it always seems to be good for me.
But sometime I just go when I can and then I have to “roll the dice".
Cheers
SD