The figures, sourced from package holiday bookings across lastminute.com's core European markets of the UK, France, Germany, Italy and Spain, show travel between September to November now accounts for 19% of annual trips, reaching 58% the size of total bookings from June to August.
Shoulder season bookings also enjoyed a 9.6% spike in bookings, compared to a more modest 1.4% incline for the summer period.
"The trend of shoulder season travel is here to stay," said Alessandra Petazzi, chief executive officer at lastminute.com, who added that travellers were favouring "shorter but more frequent" getaways that inevitably accelerate the shoulder season surge.
Travellers are also extending bookings well into the season, with November the fastest-growing month with departures up nearly a quarter year on year (23%) – though the online retailer also saw a 7% spike in bookings for September, and a 12% increase for December.
Beach breaks make up the majority (60%) of shoulder season travel, with holidaymakers continuing to avoid the heat – and the higher costs – of peak summer.
These results also reveal the importance of catering to niches and cultural events, with London bookings surging 30% year on year in the week when Radiohead played in late November.
Majorca was the top shoulder destination for the surveyed holidaymakers, closely followed by Tenerife, Crete, Amsterdam and Barcelona. Popular long-haul destinations included Marrakech and Sharm El Sheikh.
