[Rick Seaney is the CEO and cofounder of FareCompare, and columnist for Investopedia. The views expressed by columnists are those of the author and do not necessarily reflect the views of Investopedia.]

There are some things you can usually count on this time of year when it comes to air travel: Fares will be cheap in the fall; they’ll be expensive at Thanksgiving; and airlines will keep changing the rules on us. Read on for the latest about new and recent fee hikes, plus a couple of rule changes you may or may not like, but should know about.

Increased Bag Fees

JetBlue: Carry-on bags are still free, but the cost of big bags has risen. First checked-bags have jumped from $25 to $30, and a second bag that used to cost $35 is now $40.

United: The airline quickly followed JetBlue’s lead, raising prices by the same amount. Note: If you fly United’s Basic Economy, you also pay a fee for a carry-on. Meanwhile, many analysts say they won’t be surprised in the least if American and Delta are next to raise baggage fees.

International airlines: Canadian airlines Westjet and Air Canada have also been tinkering with various baggage fees; these will rise for flights taking off in October. Over in Europe, meanwhile, Ryanair will now charge for carry-ons, but will still allow a very small bag for free, providing it fits under your seat. 

Higher Early Boarding Fee

Southwest: Actually, the airline’s EarlyBird Check-In fee hasn’t increased on all flights. Some will continue to pay $15, which moves you up in the boarding line – essential to getting a good seat on an airline that has no reserved seats. However, on some longer flights or flights where this add-on is especially popular, the price will rise to $20 or $25.

New Seat Fee

United: The airline is doing what other large airlines have been doing for a while, charging an extra fee for seats closer to the front of the plane. These aren’t bigger or necessarily better seats, just closer to the front – but that could be a big deal if you have to exit your plane quickly to catch another flight. The airline hasn’t said how much this will cost, just that it will go into effect later this year. On other airlines, these fees start at as little as $4. 

New Service-Animal Rules

The airlines are making it more difficult to bring just any creature on a plane as an emotional support animal. As one media story put it, United began looking at changing its policies earlier this year when “a woman tried to bring a peacock with her on a flight.” Several other airlines are also revamping these policies including American and Southwest.

The rules, in some cases, are complicated so be sure to check with your airline well in advance before you make plans to fly with any animal. American, for example says no to hedgehogs and spiders acting as service or emotional support animals, but "miniature horses properly trained as service animals" are allowed. 

For more, see Bizarre Airline Rules You Might Need to Know.

What to Rejoice Over

We are now in the fall deal zone – or crazy dollar days, as I called it in a recent column. Autumn fares are very, very cheap, so plan a trip across the country or a flight to Europe. Earlier this week, I found these round-trip flights in October for under $400 round-trip:

  • New York to Copenhagen, $320
  • New York to London, $354
  • New York to Rome, $385

Forget the baggage and early boarding fees; they’re just minor inconveniences you need to know about to avoid a nasty surprise. The big news is air travel is really cheap right now – the perfect time to set off on a new adventure.