How to figure out the best time to buy your Thanksgiving flight (Hint: It's soon)

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You might still be enjoying the last few weeks of summer, but before you know it, it will be time to book your Thanksgiving travel plans.

But what's the best time to do so? Flight prices can be difficult to predict: Buy too early and you could miss a good deal, but buy too late and you could get stuck with high prices.

Though Thanksgiving is a couple of months away, research on historical price data — and other price monitoring tools — indicate that September is the sweet spot for saving on flights for the holiday.

"Last year, [Thanksgiving] flight prices were cheapest around mid-September," Patrick Surry, chief data scientist Hopper, an app that monitors price fluctuations and predicts future airfare, tells CNBC Make It.

This year, Cheap Air, an online travel agency, is currently tracking 11,000 itineraries for flights during the holiday season to identify the average fare for the most popular markets. Currently, for Thanksgiving flights, Cheap Air is expecting airfare to drop the lowest in September, with a predicted average price of $393.

According to Hopper's data, domestic flight prices between Nov. 21 and Nov. 25 are currently averaging around $358 round-trip, says Surry, and Thanksgiving flight prices are currently 8.5 percent more expensive than last year. 

Whatever you do, be sure to book your Thanksgiving flights before Oct. 31, says Surry. After that, prices really start to climb.

"If you wait until early November, it will cost you about $2 per day you wait," Surry says. "In the final two weeks leading up to Thanksgiving, prices begin spiking by $5 per day."

According to Cheap Air, by October, average prices will be up to $430 and by November, $500.

Hopper's Surry also recommends being strategic about your departure dates to get a better deal. He says the most expensive day to depart is Wednesday, Nov. 21, so if you can, depart Thanksgiving morning to save an average of about $68. You can also save an average of a little over $100 by returning on Monday, Nov. 26 as opposed to Sunday, Nov. 25, he says.

For more specific information on dozens of popular routes, Google Flights rolled out a new tool on Monday, providing insight into holiday price trends for 25 of the most common holiday routes based on relevant 2017 data. 

It also debuted a tool that will rate Thanksgiving flight prices on a scale from "low" to "typical" to "high" based on historical prices and prices available so far this year when you search using Google Flights on your smartphone.

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