It's 'Princess Diana weather.' Understanding the enduring appeal of the oversize sweatshirt, bike short and chunky sock look.

The air is crisp. The leaves are falling. The sun is shining. It’s not just fall weather; it’s "Princess Diana weather."

Nearly three decades after Diana, Princess of Wales, died in a car accident in Paris, her style continues to inspire headlines and influencers and dominate Reddit threads and Pinterest boards. In addition to our obsessions with her many iconic looks (the revenge dress! the jewels!) one of her more casual outfits — the simple sweatshirt over bicycle shorts, often paired with scrunchy socks and white sneakers — has become a symbol of the changing season.

"Cannot wait for princess Diana weather to return (bike shorts and sweatshirts)," read one recent post on Threads. "Happy Princess Diana Weather to all who celebrate," added an X user sharing his own spin on the trend. There's also an entire subreddit gushing over the joys of wearing long sleeves and short shorts in mild weather. It's a look that's caught on with celebrities like Hailey Beiber and Taylor Swift in recent years.

“I wouldn't say that Di's bicycle-shorts-and-sweatshirt look retained its popularity over the years," Kristen Meinzer, royal watcher and co-host of the Daily Fail podcast tells Yahoo Life. "Rather, it went out of fashion, but then came back after a generational cycle, as fashions tend to. Add to that the rise of normcore, the embrace of athleisure and the waxing interest in the royals in recent years (thanks to the Sussexes and The Crown), and you have a lot of points converging.”

Call it a classic or just call it cozy, there’s a lot to love about this look. Here's what experts say about its enduring appeal.

A seasonal shift

The thing about Princess Diana weather is that it's usually short-lived, a brief period of time when it's both cool enough for an oversize sweatshirt and still warm enough to go out in shorts. And after a sweltering summer, the sporty outfit also represents not only a reprieve from the heat but also a transition to fall, that magical time of year when the nights are cooler, the sunsets come a bit earlier and the smell of burning leaves (or at least candles that emit the smell of burning leaves) is in the air.

“There’s a very narrow window for balmy trans-seasonal weather; it's the perfect opportunity for most people to replicate the look — which has a fresh, autumnal appeal to it that never really seems to date,” says Eloise Moran, author of The Lady Di Look Book: What Diana Was Trying to Tell Us Through Her Clothes. “It's pretty much the only time of year you can mix crisp fall outerwear with bare legs.”

The comfort factor

Few outfits are more comfortable — or easier to pull together — than a sweatshirt and some stretchy shorts. And while Diana favored this pairing for her workouts, today's love of athleisure, as Meinzer notes, makes it acceptable outside of the gym too. And it's accessible particularly for those of us who don't have the budget or shopping prowess to recreate other popular Princess Di looks.

“There's a sense of ease to it that makes it so easy to re-create, plus it has a sense of timelessness that's made it a go-to for both celebrities and regular folks the last couple of years,” says Moran.

Diana's influence

For all its charms, it's ultimately the outfit's association with Princess Diana — who stepped out in sweatshirts emblazoned with the logo for Virgin Atlantic (later sold at auction for $50,000) in a clever ploy to prevent the paparazzi from taking her photo — that makes it fashionable and not frumpy. “Everyone knows it's the Lady Di look, and I think that's why people associate this aesthetic with such fondness,” says Moran.

It's another testament to the royal's larger-than-life legacy — even for those who were born after her 1997 death. Speaking to Yahoo Life last year, Rebecca Forster, an associate professor in communications at Chapman University, shared her theory as to why Diana has remained such a cultural force.

“She was set as a modern-day Disney princess by the media and elevated to [the] status of an icon,” Forster said. The psychologist added, “She died young, pretty and vastly popular — all the ingredients needed to retain that celebrity status."

Psychologist Don Grant says that "the media has a lot of power" in shaping Diana's image. “When they talk about Diana, they talk about chic, they talk about stylish, they talk about [being a] fashion icon. So I think that the media has promoted her and made her an urban legend.”

The sweatshirt-and-bike-shorts combo might be the purest example of how Diana carved out an identity for herself as "the people's princess.” After all, Diana wanted more than anything to be physically and emotionally comfortable in the world and to navigate it on her terms.

“Any princess can wear a gown,” says Meinzer. “But Diana sometimes chose to dress like the rest of us.”