Image via Getty.

We have suspicions about celebrities who happen to change their hair on exactly the same day. Did they call one another to confirm? Is there something in the water over there?

Either way Kim Kardashian, Amy Poehler, Julianne Hough and Hilary Duff all decided that it was time to mix things up in the last 24 hours.

Kim Kardashian, clearly not content with changing her hair from long to short, then platinum blonde and back to black in the space of a couple of months, stepped out with a longer ‘do that we can assume is thanks to extensions. Unless her hair has super powers.

Unless she has magic powers - Kim's hair is thanks to extensions. (Image via Getty)

Actress Julianne Hough changed her normally blonde hair to a candy floss-inspired shade of pastel pink.

"So why did I decide on the color pink this time? Because pink is the color of kindness," Julianne wrote on her blog.

"You know when you just need a change? Well I went big!"

Yes, yes she did.

Julianne went big with this change. (Image via Instagram)

Comedian Amy Poehler ditched her trademark blonde hair for a punchy auburn colour that she debuted on stage at the The David Lynch Foundation’s DLF Live Celebration Los Angeles yesterday. We haven’t been able to track down any vintage Amy Poehler hair pics where she’s not blonde, so this is a very big move for the 43-year-old.

Amy Poehler rarely changes her hair. But we're glad she did! (Image via Getty)

Not content with her turquoise hair change a few weeks ago, actress Hilary Duff has clearly decided she’d prefer to jump on the grey-hair trend, sporting silver hair. But the 27-year-old admitted her changes in hair colour are more due to the original dye washing out than a stint in the salon.

"It's fun right now it kind of takes on different tones every time I wash it,” she told E! News.

Hilary has jumped on the grey hair trend bandwagon. (Image via Getty)

Is anyone else feeling inspired to change their hair now it’s autumn? These recent celebrity hair transformations might convince you to book an appointment with your hairdresser.

The best celebrity hair transformations

Kim Kardashian

Julianne Hough

Hilary Duff

Amy Poehler

Khloe Kardashian

Katy Perry

Chrissy Teigen

Image via Instagram.

Kate Waterhouse

RihannaRihanna does good fringe. Image via Getty

Christina HendricksMad Men star Christina Hendricks has gone back to her blonde roots. Image: Courtesy of Clairol.

Hilary Duff

Hilary says mermaid, we say Kylie. Image via Instagram.

Tyra Banks

Sam Frost

Christina Aguilera

Image via Instagram.

Idina Menzel

Sarah Hyland

Image via Instagram

Ellie Goulding

Jessica Alba

January Jones

January Jokes

Giuliana Rancic

Giuliana Rancic

Cara Delevingne

Cara Delevingne

Kim Kardashian

WOAH. Kimmy K shocked us all when she bleached the bejeezus out of her naturally ebony hair. The process reportedly took several hours.