(NEW YORK) -- Planes are full and that means even higher prices for holiday travel. A new report from airline trade group Airlines for America released Thursday shows demand strong and planes flying at 85 to 90 percent capacity over the 21-day holiday travel period.
About 42 million passengers will fly between Monday, Dec. 17, 2012, and Wednesday, Jan. 6, 2013.
Translation: The time for holiday airfare bargains is up. Non-stop ticket prices Christmas week are nearly double what they were at the beginning of the month, and rising by the day.
"Every day you wait for your virtual airline ticket, add about $7 to $8 ... and if you wait until the second week in December you could start adding about $15 a day," said Rick Seaney, CEO of FareCompare.
The average domestic air fare is now $414, according to Travelocity, nine percent more expensive than last year's holiday season. The most expensive days to fly, up to $500 or more a ticket, are Dec. 21 and 22 and on the return Dec. 30 and 31, and New Years Day.
The cheaper days to fly? Christmas Day, and the three days following. Flying on those days can save as much as $330.
"You're going to sacrifice price for convenience, but you'll also encounter fewer crowds at the airport," said Genevieve Shaw Brown, ABC News Travel and Lifestyle Editor.
Adding injury to the already insulting high holiday fares this season: Baggage. It, too, increases the cost for travelers this holiday season. Airlines charge excess baggage surcharges that start at $90 on top of the now-normal checked bag fee, and the scales at the airport are not always accurate. Use a home scale to make sure your bags aren't overweight., experts advise. "Fees can range wildly from as low as $100 for bags over 50 pounds to over $275 depending on the airline," said Seaney. "It can cost really more than your airline ticket on a short-haul airline flight. The checked bag starts out as $50 round-trip, this [excess bag fee] is on top of that... The only exception to that is JetBlue and Southwest where your first checked bag is free."
An ABC News investigation last year at this time showed five percent of airport scales checked nationwide were off by at least half an ounce, enough to add costs. New York had the highest rates of inaccuracy with 48 troubled scales at JFK alone. San Francisco had 13 off; at Dallas, seven were faulty.
Copyright 2012 ABC News Radio