I am heading from Dallas to San Francisco for a weekend in June. I've heard there are websites out there that can tell you specifics around how far in advance you should look for flights. Lately, if I book too far in advance, by the time it gets closer the flights have gone down quite a bit. But then you don't want to run the risk of flights booking up....

Thoughts?! Thanks much!!

I use kayak.com. It shows you graphs of the fares over the past 3 months so you can spot trends or find out if now is a good time to buy. It also shows you the best days to fly if your dates are flexible.
Keep checking regularly and sign up for email alerts of low fares.

I paid $255 for a flight to Miami in April. It's not super low but it's DIRECT and during school vacation week so I'm happy with the price.

Try Farecast: http://farecast.live.com/about/howWorks.do

Those websites that track air fares are interesting, but not really useful, and I'd never rely on them versus my own diligent shopping. There are sales all over the place lately and many, such as Kayak, aren't always up to date with the latest sale fares. For example, I've been shopping for fares to Ireland and the fares have been much lower directly on Aer Lingus than any of the other searching sites.

No one, and no software, can predict when fares will be lowest.

At some point, when fill rate for your route/dates is more favorable, the fares will start going up.

You can watch for fares to go as low, or nearly as low, as they've been previously. Then, book when the fare is appealing. I'd be more distressed if I didn't book and had to pay a lot more, than if I did book and the fares went down a bit.

Thanks, this really helped! At least on kayak I can see what the ranges are and what would be reasonable. I think I'll wait and cheak back in month... looks like too far in advance. Thanks!

I've been using yapta.com to track fares. They promote that they will get a refund to you if the fare goes down by a certain number.

Waiting and checking back in a month is not such a good idea. A LOT can happen over a month. When my dates are not flexible and I'm going no matter what, I check almost every day. And, I've saved a bundle. I really believe (and this has happened with hotels, too) that I've often found "mistakes".

And, signing up everywhere for e-mail alerts does produce a lot of e-mail (and much of it useless), but you never know when a bargain will fall into your lap you wouldn't have known about otherwise.

I read somewhere that airfarewatchdog.com is good for un-advertised, short lived, and "fat finger fares".

Again, once your preferred flights/route fills substantially or completely, there will probably be no bargains.

Note also that San Francisco is traditionally very busy in June, particularly with huge medical conferences. So same goes for shopping hotels.

I second the idea that you need to check daily not just recheck in a month. You might miss the the deal you're looking for.
Prices go up and down daily and it's pretty much unpredictable when the lowest fares will be available but supply and demand do dictate the price so for popular routes at peak times you must be vigilant for a good deal.