The news: Travel seasonality may be growing less predictable. Extreme summer heat is pushing some travelers toward the fall, better price-discovery tools are making overlooked deals harder to secure, and airlines facing elevated fuel costs are leaning into higher-margin demand.

The result is that the deals travelers once found during the off-peak shoulder season, generally September through mid-November, are becoming harder to find. When Expedia compared prices across the 10 most popular US destinations, it found fall lodging prices were 20% higher than during the summer, while airfare was 2% higher.

Zooming in: Several factors are converging to drive up demand (and prices).

Extreme weather is changing travel preferences. Europe experienced record-high temperatures this summer, with the effects magnified by limited access to air conditioning and high nighttime temperatures. Wildfires also raged across the western US, Canada, Greece, France, and Spain. Those conditions prompted some travelers to reconsider when they visit traditionally popular summer destinations, disrupting typical seasonal patterns.

It’s easier than ever to hunt for a deal. Travel aggregators, search engines, and AI make it simpler for consumers to identify lower prices. But as more travelers chase the same deals, they can drive demand toward previously overlooked periods and destinations, eventually eroding the savings they were seeking. That trend could accelerate as AI adoption grows. Already, 76% of US AI users use AI to compare prices and look for discount codes at least some of the time, per a PwC consumer survey.

Airlines are leaning toward affluent travelers as costs rise. The war in Iran is weighing on airline profits, pushing carriers to favor routes and seats that generate the strongest returns. That could mean cutting less-profitable routes and reducing the availability of lower-priced seats while emphasizing premium cabins. Higher-income consumers are expected to account for 55% of travelers this year, according to Deloitte, and their greater willingness to pay for premium experiences makes them valuable in a higher-cost environment, benefiting airlines like United and Delta.

Implications for travel marketers: The more travelers shift trips toward periods that were traditionally off-peak, the less off-peak those periods will become. While unusual conditions are accelerating that shift this year, two important drivers—extreme weather and better price-discovery tools—aren’t going away.

That means travel companies may need to rethink when and how they spend to stimulate demand. The industry has traditionally used discounts and advertising to fill predictable slow periods, but those investments may be less necessary if demand naturally migrates into September and October.