To determine day-to-day common rates, KAYAK will take all prices for each day in advance of departure over the past year for flights from London Heathrow Airport to Austin, eliminates the best 0.1% to account for outliers, and then can take the average of many of the values for monthly. https://businessclassflightstoaccra.blogspot.com/2024/05/how-to-plan-round-way-trip-to-vegas.html