By Dorothy Tucker

(CBS) — During this deep freeze, are you dreaming of thawing out on a warm, tropical beach somewhere?

But when should you book your escape to get the lowest price?

CBS 2’s Dorothy Tucker runs down specially conducted research.

Airline tickets are expensive, and you can expect prices to keep rising. That’s why knowing when to book and buy could save you a bundle.

Abby Hoppes said she wants to fly to Europe in June. The cheapest flight she could find was $1,300.

Now is not the best time to book a business class from sydney to munich flight from Europe, according to researchers at the Airline Reporting Corp., which processes millions of ticket transactions every year.

ARC specifically looked roundtrips from Chicago’s O’Hare to popular cities in Europe, in 2011 and 2012, for CBS 2.

The period 11 weeks before departure is typically when the lowest ticket prices show up, says Chuck Thackston, managing director of data and analytics for ARC.

Using that framework, for example, a traveler would book a flight March 16 to travel June 1. A flight to Dublin would cost $1,020; Warsaw, $1,187; and London, $1,213.

The data provides a different answer if you’re flying within the United States from O’Hare. The best prices are typically 32 days before departure.

“The data that we looked at was for economy-class tickets and based on a round-trip ticket purchase,” Thackston says.

And then there’s the Caribbean.

“I actually go out to Trinidad for Carnivale in February, and I book those flights six months in advance,” traveler Kelly Georgetti says.

Smart move. A roughly six-month lead is exactly what researchers suggest. Book in July for travel starting in January and you’ll find the lowest fares: $509 to the Bahamas, $537 to Jamaica and $627 to Aruba.

Other ways to save money:  Look for alternative airports to fly into like Manchester, England, instead of  London’s Heathrow.

Click here to review ARC’s data. The company cautions that “findings are solely based on historical data. ARC does not imply or guarantee any future ticket prices from any airline carrier, regardless of purchase date, location, or time.”

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