When looking for the cheapest time of year to fly, it's important to keep two things in mind: the start of the U.S. school year and the approach of colder weather. Those industry-designated "dead zones" are the most unpopular times to travel, says Rick Seaney, CEO and co-founder of FareCompare.com
. He advises booking your next vacation for the period during the last week in August through the first week in December (not including the week before Thanksgiving). You'll save even more money by searching for flights on Tuesday, Wednesday and Saturday, which Seaney says are the least expensive days to fly.