The cheapest months to fly are loosely based around prime vacation times.

First, let’s talk about where the normal rates come from.  Most flyers are business people who fly in on Sunday or Monday and out on Thursday, Friday, or Saturday.  I cover more about cheapest days of the week to fly in my post on when to buy plane tickets.  They fly year round except for major holidays and the end & beginning of the month to a lesser extent (due to businesses busy closing out the previous month).  They set the demand for plane tickets & what the prices are.

Big Holidays

With business travelers setting the normal price & schedule, whenever there’s an influx of demand for plane tickets, prices begin to increase.  Let’s make a quick list of the big holidays:

Memorial Day, Fourth of July, Labor Day, Thanksgiving, Christmas, & New Years

However people don’t travel on these days, they travel around them, which incidentally makes flying on these days cheap from lack of demand.  With most American vacations lasting just 4 days, taking weekends into consideration, & understanding that some folks “front-load” their vacation while others “back-load” it, the week before & after a major holiday have increased demand for plane tickets.

cheapest months to fly - holidays

School’s Out!

The next big vacation time is summer.  Kids are out of school and families travel em masse.  Interestingly, non-business travelers probably outnumber business travelers because work doesn’t stop for summer.  Taking into account there’s less pressure than holidays for when to leave & come back (because kids don’t have to be back in school), the phasing in & out of demand for flights is more like 2 weeks.  So…

Beginning at the end of May through mid August, people are flying more so prices are higher.  They’re not the cheapest months to fly.

cheapest months to fly - summer

Let’s Hit the Slopes.

Finally, there’s an impressive number of people that travel for skiing, and because this is a very localized activity, most people have to travel distances to carve up some fresh powder.  While families may not be flying, singles, young professionals, & business travelers do travel in numbers large enough that prices begin to increase around winter.

December through mid-March are not the cheapest months to fly.

cheapest months to fly - winter

Off-Peak Months

These 3 factors lead the cheapest months to fly being:

mid-March through end of May, and mid-September through mid-November.

Rates may begin to increase on the outsides dates of these timeframes, but not in meaningful numbers.  Taking this one step further, buying tickets for these months should happen around 90 days in advance.  Use Kayak to search for flights & their price advice to help guide whether to buy or not to buy.

cheapest months to fly - good calendar

Bottomline – The cheapest months to fly are mid-March through mid-May, and mid-September through mid-November.