When is the best time to buy a plane ticket?

As far in advance as possible.

JLeslie, is correcet. Sooner the better.

If you want tickets for Christmas vacationing, now.
Labor day weekend, yesterday.
For your occasion, maybe sometime this or next month, so that you’re really prepared. But you should never ever be too early, like 1 year early. That’s torture.

But, as everyone has said so far, the sooner the better. Probably 1–2 months in advance. Or maybe 3.

Ticket prices can change daily. If you can figure out the pricing system, let us know. Best practice is per @JLeslie

I forget – it’s either Tuesday or Wednesday around noon (don’t ask why but I’ve heard this before)

When all the TSA idiots are on vacation! : )

Ticket prices change weekly based on how many people are expected to fly vs tickers purchased. As you will notice if you buy a ticket really far out, there is a standard ticket price for any date you choose. However if you know there are no holidays or popular travel days when you are planning to fly, you might see a drop in ticket price because the airlines will try to sell more seats on the flight.

My rule of thumb is to monitor it about 4 weeks out, unless i know I’m traveling around a holiday, then it’s months in advance. Ticket prices will sky rocket within the 2 week mark, then drop back down to the lowest price about 4 days before (only if they is still a considerable number of seats available for the flight).

The biggest tip is to actually fly on a Tuesday or Wednesday. Friday is the most expensive day to fly, and Sunday is up there as well. Connecting many times is much cheaper than non-stop, although DC to San Diego will have lots of competition, so the prices should be decent. @Silence04 makes a good point about holidays. Sometimes if you fly right before or after holidays you can get a really good deal. Like the Tuesday after Presidents day, the Tuesday before Thanksgiving will be half the Wednesday price most likely. Around Christmas, Christmas day is usually much cheaper then a day or two before.

As far as October goes, Columbus day is observed October 10, a three day weekend for many, so travelling Sunday back home might give you a good price, but flying out Friday will likely be expensive. I think Yum Kippur is Saturday the 8th this year? Not sure if the airlines watch that holiday or not? Many Jews take it off from work even if they are not observant, so they might have taken off the Friday for a long weekend. Also Halloween at the end of the month. Not that Halloween is a huge travel holiday, but there is probably some increase, especially to cities like Vegas and NY.

Not something that I would do myself, but someone adviced me recently that it can be very profitable to wait until the day of departure, or one day prior.
But you must be pretty flexible in your time and have low stress level, I would think.
This was about a ticket for a European flight, I don’t know if this goes up for the USA.

@rebbel It’s generally just the opposite. Plane fairs are jacked up for the desperate to be there. The system actively capitalizes on business travel, emergencies, and last minute plans by jacking up prices enormously the last day or two before a flight. Sometimes there are last minute deals, but it is really not worth the risk of hoping for one of them.

In contrast, the cruise industry runs last minute deals constantly.

In my experience, Tuesdays are indeed a cheaper day to fly.

There isn’t one. Picking the best time is a form of speculation. It’s like buying gas this week or next week. Or oil for heating now or in 6 months. When sales are slow tickets can actually get cheaper because planes need to fill up. The variable part of the costs per flight are relatively low compared to the fixed costs.