Hurricane Sandy is set to hit the North East coast of the US. It is expected to be one of the worst in decades, and in preparation, the airlines have cancelled more than 7,000 flights.
So what happens if you are affected by the cancellations: what can you do?
The stormA state of emergency has been declared in New York, as the National Weather Service is predicting 80mph winds for at least 24 hours - along with high tides and heavy downpours.
Major carriers are cancelling all flights in and out of New York's airports, while Philadelphia and Newark have cancelled 1,200 flights. BA and Virgin Atlantic have cancelled all their flights to and from New York, Washington and Boston - and some to and from Baltimore and Philadelphia too.
The impact of the cancellations and delays are likely to spread beyond these airports, with knock-on effects across the US and Europe.
Your rightsIf you are directly affected by the cancellations, all the airlines are operating what is known as a 'flexible travel policy' which lets you make changes to your reservations (or to cancel) without paying a fee. If you contact your airline direct it will help you though the process and explain the rules surrounding re-booking.
StrandedIf you are stranded overseas, if you are with an EU airline, they will have to follow the EU rules, and cover reasonable meals and overnight accommodation until you can get a flight out. The fact that cancellations are due to 'exceptional circumstances' means they don't have to pay compensation, but they do have to look after you.
However, you will also have to follow local safety advice, so you can still expect a certain amount of local disruption.
If you are with a US airline, there is no blanket policy, so you'll need to speak to your airline and find out what their rules are. Don't go to the airport to do this, you're likely to get a quicker response on the customer services telephone number, without the panic and stress of being at the airport.
Bob Aitken, travel expert at Moneysupermarket, says that often they will not offer any help at all, so you will need to turn to your travel insurance. He adds: "Call your travel insurer and let them know you will be making a claim. Check what they will and will not cover you for, and then make sure what you arrange is within the rules. You also need to make sure you keep receipts for anything you want to claim for."
Knock-onIf you are affected by knock-on effects when flying within the EU or with an EU carrier, you will not have the same cancellation rights, but you will be entitled to assistance if you are stranded at the airport. It depends partly on the distance of the journey but after three or four hours you will be entitled to refreshments and two free phone calls. If you are stuck overnight, you are entitled to comfortable accommodation.
Aitken says: "If you are flying anywhere over the next few days, it's worth double-checking that there are no cancellations before you set off for the airport. Most flights will not be affected, but it is worth checking."
OutgoingHe adds that if your outgoing flights are cancelled, you will face different issues. If you booked a package, you should have an opportunity to rebook. If you booked separate flights and accommodation, you need to speak to your airline and work out whether their rebooking policy works for you, or whether you are better-off cancelling.
You will then need to contact your hotel and any car hire company or additional company you have made a booking with. You should cancel with them, as you may not have to pay the full amount outstanding. Aitken says: "You should then check with your travel insurer for whether they cover 'irrecoverable costs' which will pay any cancellation fees."
Clearly the storms are going to cause massive disruption, and many thousands of people will be stranded or disappointed. However, if you are proactive and seek help as soon as possible, any difficulties you face should at least not be too painful on the pocket.