May be just a silly thing but it had been bugging me in the last few days.

We know that seasons in Westeros are of irregular length and last years. Given that on Earth a year is 'a turn of seasons' and it's likely that the cicle of the seasons was the first way to count years, before precise astronomical measurements were made, how is a Westeros year defined ? On what is it based as measurement of time? I don't recall any passage in the books about this but it could have escaped me, any ideas?

Well, seasons are very subjective in GRRM's world. The way that Westeros experiences seasons is not the same way that all the lands of his world experiences seasons. Consider the fact that Summer being over is big news across Westeros, but is never mentioned in the Free Cities or in the cities along Slaver's Bay where Dany is. So I think it's safe to assume that without the consistency of marked seasonal variation anywhere (within one place or from place to place), they probably came up with some other cycle to measure a year by - perhaps a lunar or solar cycle that did not require particularly advanced astronomy. Someone in Valyria probably developed it long before the Doom.

The Citadel probably counts a certain number of days before announcing the coming of a new year.

It may well be either way, I wondered, though if it was mentioned anywhere in the books...

I haven't read it anywhere, but they keep track of their name days and base their age in year on them, so it has to be either of the above.

I'd suggest moon cycles would be easier to track than days, but it's still arbitrary (why would twelve cycles make a year, anymore than eleven or thirteen?).

In the books, there seems to be a cycle of harvesting, so that might suggest the existence of a sub-seasonal cycle (for example, if it's winter, there would be a winter-spring, winter-summer, winter-fall, and winter-winter), and that sub-seasonal cycle might be yearly.

Or it might be if a dragon hatches from its ancient slumber, and sees it's shadow, then it's a new year.

Interersting thoughts. If my vote counted, I'll choose the last option, though.

Eldil said:

That's what I had assumed as well. It seems there are still traditional seasonal changes on a yearly basis while Winter/Summer also have a global climate effect like an Ice Age or something.