On Delta Airlines’s third-quarter earnings call Thursday, president Glen Hauenstein said the spikes in travel the industry typically expects in July and August have dropped off—and the boiling heat is to blame.

As a result, Delta, alongside other airline heavyweights, are slowly moving their schedules to better accommodate the shoulder season—early spring and mid-fall—where European travel is gaining steam. Indeed, those July and August peaks are giving way to September and October peaks, Hauenstein said, when the un-air-conditioned Italian coasts and Parisian arrondissements are less likely to give travelers heat stroke.

“The weather in Europe in August is really hot,” Hauenstein said, adding those with the ability to change their annual vacation time frames are moving into “more temperate months.” Even those might be in short supply in the coming years: Summer 2024 was the hottest on record in the Northern Hemisphere, following a string of record-breaking years beforehand. 

Of note, primarily leisure travelers are switching up their habits, Hauenstein said; corporate travel hasn’t budged. 

The seasonality line of questioning came from Duane Pfennigwerth, an analyst at investment bank Evercore. “There’s a bit of noise right now…with hurricane impacts and with holiday shifts here in October,” Pfennigwerth said. “But as we look at volume growth for the industry, it looks like trends are following much more [of the] 2019 baseline than [2023].”

Hauenstein chalked that up to the “shift of the Jewish holidays into October” as well as “of course, the hurricanes.” 

“But I think if you take a broader longer-term vision, we have seen really, August, in particular, but to a slightly lesser extent, July become less peaky, particularly in long-haul international—and that September and October are becoming prime travel months,” he said. The gradually earlier return to schools will contribute to the trend, he added—and corporate summer travel to Europe, if any exists, will likely move into fall as well.

That September and October peak will be followed by a pronounced drop-off in November, Hauenstein added, due to the election, which historically leads to a drop in domestic travel. “And then again, as soon as the week after the election is complete,” he said, positive momentum will return “into December and really all the way into January.” During those months, travelers will be back on board, hoping for some of that summer heat.