I told some friends of mine that I was about to book flights to South America and they replied: “Make sure you do it on a Thursday”.
Apparently, when booking their own flights to the same continent, they had noticed daily fluctuations in the price with a pattern emerging such that booking on a Thursday seemed cheapest. They did some Googling and found similar sentiments on discussion forums: flight prices vary depending on the day of the week you book.
I haven’t conducted an elaborate study myself but there is definitely a pattern that isn’t just the cost going up closer to the date and ended up booking my flights following a Thursday low.
So, next time you’re booking flights with a bit of notice, check the prices over a few consecutive days to watch for the nadir.
And if you don’t believe me, try The Economist (who actually recommend Tuesdays).