To calculate monthly normal costs, KAYAK takes all prices for each and every month throughout the last year for flights from London Heathrow Airport to Austin, gets rid of the highest 0.1% to account for outliers, and after that will take the median of all values for every month. True https://whitemagictravels.co.uk/blog/5-things-to-remember-when-booking-flights-to-los-angeles-from-london/