We've been taught that light hair belongs to spring and summer: beach afternoons, hot days, and the urge to connect with nature. For those who aren't naturally blonde, we thought fall's arrival and its moodiness called for darker hair—for example, cherry cola and cinnamon spice hues. Last week, we got a much-needed reminder that blonde belongs to no season—and might actually be perfect for fall. In lieu of friendship bracelets, coordinated phone cases, or matching tattoos, sisters Devon Lee Carlson and Sydney Lynn Carlson both went Y2K blonde in what we consider the ultimate and most iconic sign of true sisterhood.

On both sisters, celebrity hair colorist Jacob Schwartz used Schwarzkopf Professional's IGORA Royal for the smudge, Vario Super Blond Plus for the highlights, IGORA Vibrance to fill in the roots and add gloss for a fresh, creamy color that he calls 2000s blonde.

Devon Lee Carlson debuted her new hue in the most Y2K way imaginable: posing in a car with a French tip manicure and rectangular purple-tinted sunglasses.

Then, her sister followed suit. For both, the color feels natural with deep roots and is far from the bleach blonde that we might think of when we think of lighter hair. Instead, it's reminiscent of Mandy Moore in The Princess Diaries, Amanda Seyfried in Mean Girls, and Jessica Alba in her prime. It's warm for fall, but also unmistakably blonde.