Scandinavian Airlines says that planes from London to Stockholm on 21st, 22nd and 23rd December are "already filling up."
Planes in the opposite direction, from Stockholm to London, have a fair number places remaining for the run up to Christmas but flights between Christmas and New Year are "pretty full up already," according to Monica Hultberg, spokeswoman for SAS.
"If you want to be certain, now is the time to book," Hultberg told The Local.
Flights from Stockholm to the US are also being booked up by Christmas travellers. There are places left on SAS direct flights from Stockholm to New York on 21st and 22nd and 22nd December, but all flights are "starting to get full," according to Hultberg.
The lowest available price for a one-way direct flight from Stockholm to Newark on 22nd December was 11,986 kronor including taxes, according to the SAS Sweden website on Tuesday afternoon. Flights on the same day from Newark to Arlands were being advertised at 10,873 kronor.
Tickets with other airlines are also getting pricey. While Ryanair's flights from Stockholm Skavsta to London on 23rd December were still selling for a humane 616 kronor one-way including taxes, people flying in the opposite direction on the same day will have to pay at least 1,296 kronor one way. The situation was similar for Ryanair flights from Gothenburg to London.
Nonetheless, there are still some bargains to be had, with Ryanair tickets from Gothenburg City to Glasgow Prestwick on 23rd selling for just 217 kronor one way.
British Airways flights from London to Stockholm on 23rd December are selling for £312 one way, or 4,258 kronor. While prices in the other direction prior to Christmas are lower, they rise in time for New Year, with Stockholm to London on 30th December already starting at 2,806.
"People should book now if they want to be certain of getting home during the Christmas period," said Hultberg.
Even within Sweden, passengers are being advised to book ahead for Christmas travel. Trains out of Stockholm to Norrland and southern Sweden are expected to be fully booked well before Christmas. The fast X2000 trains from the capital to Malmö and Sundsvall are expected to be booked up first.
Airlines and train company SJ expect 22nd and 23rd December to mark the height of Sweden's Christmas exodus, according to news agency TT.