The optimum time to buy US flights is 70 days before departure and the cheapest tickets are typically for Wednesdays, according to analysis by of almost a billion fares and over 8,000 markets in the US.

The analysis showed Wednesday prices averaging $100 less per fare than Sunday, the most expensive day to fly. February was listed as the cheapest month in which to fly, with December the priciest. Longer lead times were needed to find cheaper summer flights, with winter needing less of a booking window to land good deals.

Fares “remain volatile”, the report said, and change 49 times on average and by an average of $43. “In 2023, the booking window that offers the lowest flight prices is approximately 1.5 to 5.5 months before departure,” said, putting some of the flux down to “today’s high travel demand, staffing shortages, and fluctuating fuel prices”