Britons are expected to make 5.7m trips abroad this month as wet weather over the summer and post-Olympics demand boost September bookings.
The figures come from a survey by Travelex, which said a quarter of those heading overseas were taking late breaks as they had not wanted to miss the Games.
Nearly half (45%) said they did not take their usual summer break during the school holidays this year, and nearly a quarter (23%) revealed this would be the first time they had gone away in September.
The most popular destination for September is Spain, with Egypt and Turkey among other popular hot spots.
Elvin Eldic, UK regional manager at Travelex, said: It's clear that this is a great time of year to be heading away to catch some last-minute summer sun following one of the wettest summers on record. Mandy Round, general manager at easyJet Holidays, added: As soon as the last race had been run and the Olympic torch extinguished, our holidays website saw an uplift in bookings in September not just to beach destinations such as Majorca, Egypt and the Costa del Sol but also to city break destinations. Meanwhile, the Post Office predicts strong winter-sun bookings for Vietnam, Brazil and Mexico after their currencies sold well this summer.
Vietnam's currency sales soared by more than two-thirds to make it the Post Office's fastest growing currency for summer 2012 Andrew Brown, Post Office head of travel money, said: It may be no coincidence that the destinations which have notched up big increases in currency sales during the summer have been ones where sterling has most surged in value. The boom in demand suggests that holiday makers are becoming increasingly canny and watching exchange rates as well as seeking out keenly-priced packages before deciding on their destination. The strength of sterling suggests that European short breaks could enjoy a renaissance this autumn.