NEW YORK ( MainStreet) — Want to know when to buy your tickets for spring break? CheapAir.com might be able to help. Earlier this month the website posted its Spring Break Flight Index , a stock market style ticker stream that tracks the prices of flights to popular destinations on a daily basis. Instead of showing airfare for specific airlines or tracking a given market, this index creates a snapshot of how prices are moving for flights in March overall.

The result is a Dow Jones-like index that lets users compare the market for airfare at any given moment. If prices have dropped relative to last week, now might be the right time to buy. If they jump, it might be wise to hold out and see what happens. If, as now, prices overall have been climbing steadily for the past two weeks, it's probably too late to grab a good deal on this year's vacation, but the data will remain valuable down the road when it comes time to start planning in 2015.

The Spring Break Flight Index is the spiritual successor to CheapAir's holiday index , which posts the same information for flights over Thanksgiving and Christmas.

This is a tool, according to CEO Jeff Klee, that's all about finding the trends. Like an investment banker looking for just the right time to invest, the index allows users to see how prices in general move over time. If it looks like the numbers overall are swinging in your direction, now might be a good time to buy that trip to Aruba.

The index tracks prices to the 38 most popular spring break destinations based on tickets bought for travel between March 2 and March 30 as well as Easter weekend. Although named for college vacations, Klee said that he hopes this information will help a much wider audience. Mid-March, he said, is a popular time for families to take trips since people often want a break from winter weather and many schools have time off as well.

Florida remains this year's most popular destination, he said, with close runners-up in perennial favorites such as Mexico and the Caribbean.

Unfortunately, by now it may be too late to cash in on good deals for much March travel. Instead Klee recommends trying other ways to game the system. In particular, timing your flight by day of the week or hour of travel can make a big difference in the sticker price. Off-hour flights sell for less than those at a convenient hour, although they generally involve getting to the airport at a horrible time of day.

According to the website's data Tuesdays and Wednesdays are the cheapest days to fly and prices spike, unsurprisingly, on the weekends. The difference in airfare can be substantial, with midweek prices sometimes as low as two-thirds the amount of a weekend trip.