In trying to score the cheapest airfares for the holidays, when you book a flight often matters just as much as your travel dates. And this year, booking early is particularly important as airfares creep higher, new Google data shows.

Flights for travel around Thanksgiving will be cheapest in October, while people traveling around Christmas should lock in their itineraries by around Halloween, according to Google Flights.

When to book flights for optimal deals

It's best to book as early as possible when your travel dates are relatively fixed. For Thanksgiving, consumers will find the lowest fares 34 days before departure, according to Google Flights, which based its findings on five years of flight data. Thanksgiving is on Nov. 26, making Oct. 22 the best day to book travel for the Wednesday before the holiday. For the lowest fares on Turkey Day trips, travelers should aim to purchase tickets between 57 and 21 days before departure.

For flights around Christmas, the lowest fares will be available 56 days before departure. Travelers can land better deals between 33 and 67 days before their trips, according to Google Flights (as of Oct. 5, there are roughly 80 days before Christmas). The best flight deals will emerge between late October and mid-November, according to Google.

Other ways to save

To save money on flights, experts also recommend traveling off-peak, when fewer people will swarm the nation's airports. Data from the fare aggregator Hopper shows that traveling on Monday or Tuesday before Thanksgiving, rather than on Wednesday, can yield savings. Avoid returning on Sunday, Nov. 29, the company said.

The same advice applies around Christmas. Hopper advises avoiding flying on Dec. 18, 19 and 20 and on Dec. 27, the Sunday after Christmas Day.

Americans should expect higher-than-usual flight prices due to the Iran war, which has raised oil and jet fuel prices, the largest expense for airlines after personnel. Before the Middle East conflict began in late February, jet fuel averaged $99 per barrel globally, according to the International Air Transport Association. It peaked at $209 in April and hit $195 a barrel in mid-September, IATA said, citing data from S&P Global Energy Platts.

Hopper data shows that domestic round-trip airfares for Thanksgiving are averaging $402, up 31% from last year. Domestic round-trip Christmas flights are averaging $452, up 23% from last year.