Cheryl famously ditched her brunette locks after getting dumped by US X Factor, but the change also coincided with more sunlight and longer days, so we're thinking it was pretty good timing generally. Her new blonde crop breathes new life into her look – and there's nothing better than short hair in the summertime.

It's only a slightly subtler shade, but the highlights in Olivia's hair make all the difference in the summer - lightening her polished look.

A natural blonde (it's true!) Leighton often takes her summer breaks from Gossip Girl as the perfect opportunity to revert back to her natural hue.

Ms. Watson swaps her brunette crop for a lighter, golden hue once the mercury rises, showing off her pixie features to perfection.

What a transformation! Jessica looks completely different when she ditches her natural brunette locks for a peroxide blonde shade. Luckily, her colouring and green eyes ensure she can pull off both looks with style.

Jenny from the block often swings between darker and lighter shades of brown, but goes all out with blonde highlights during the summer.

It's hard to believe, but she of the long raven locks was once blonde.

Ashley Olsen distanced herself from her famous sibling by opting for this darker hue for winter, giving her a much more sophisticated look. It certainly makes a change from the duo's usual dirty blonde boho waves.

Shock! Horror! Alanis Morisette made this terrible transformation from brunette to blonde a few years ago – she might be embracing a lighter look for summer, but the jury's out on whether or not it suits her...

Beyoncé often sports blonde locks, but really turns up the volume in the summer time, with more peroxide and bigger curls.

See the starlets who give their hair sexy seasonal tweaks to suit the changing seasons. For the likes of Keira, Jen and Sienna, turning a sunny summer style into a sexy winter 'do seems effortless - and it works... 

The stunning Keira swaps her relaxed blonde waves for a more dramatic rich brunette look to take her from summer to winter.

Angelina knows that turning a sunny summer look into a sultry winter style requires a dramatic colour change.

Come summer, Jennifer prefers a relaxed, tousled look, but in the colder months she reaches for her trusty straightening irons for a more sleek, polished 'do.

From relaxed and 'boho' in the summer to full-on red carpet glamour for winter - Sienna knows how to make maximum impact with her locks, whatever the season.

Mischa always keeps her locks loose and lengthy - but swaps the shade to suit her skin tone depending on the season, opting for these beautiful honey highlights with a tan in summer, then pale and interesting with a deliciously rich brunette come winter.

'Superman' starlet Kate goes for relaxed and loose in the summer, then slicked back and polished in winter.

From beach babe to sultry beauty - Jessica goes from shimmering, honey-hued waves to a glossy, chocolate-coloured chignon.

We all know natural redhead Lindsay loves nothing more than a spot of dye - and she chooses her colour to suit the season. Blondes have more fun with a tan, whereas brunettes look fabulous with porcelain skin.

What a difference a colour makes! Born-to-be-blonde Cameron shocked us all when she went brunette last winter, but come summer '07 she had gone back to her roots and became a sunny Californian blonde once again. It will be interesting to see if she'll be hitting the dye and re-joining the dark side this winter...