All summer, celebs have been stepping out with rainbow-bright-pink or cool, pastel-purple hair. (We're looking at you, Nicole Richie.) While we're tempted to test-drive it for a girls' night out or weekend music festival, it's not necessarily a look we're comfortable keeping come Monday morning.

Fortunately, it is possible to rock rainbow hair for a day or two -- and it's easier than you think.

Whether you want to punch up your blonde hair with a lilac hue, or test the waters with a few strips of rose gold, we found the products that let you wear it for the weekend (or your week off) and wash it out before work. These temporary dyes, chalks and even clip-ins let you channel a '90s Gwen Stefani -- if only for a day.

Perry has pretty much lived out our childhood "My Little Pony" dreams of playing with every Technicolor shade imaginable -- this green ombré look included.

Try this: Get the two-toned shade by working with small sections of hair, rubbing in ColorSmash Hair Shadow in St. Martini, $15. Start towards the top of the head but concentrate on the ends. "Setting it with hairspray is a really good trick [for keeping color in place]," says London-based hairstylist, Nicole Kahlani, whose trendy hair creations can be seen in ads for TopShop and Nasty Gal, plus on the boys of pop rock band 5 Seconds of Summer. "Then, you can just literally brush it out or wash it out that night."

Who it works on: Because ColorSmash is so pigmented, even dark haired girls can get the electric hue with a deeper shade like So Jaded. Just be sure to rub more onto the hair for bold color, or brush through for a more pastel shade.

The London "It" girl's '90s style wouldn't be complete without a complete hair color change-up every so often.

Try this: For Ora's blue and purple pony, brush on Bleach London Hair Crayons in Washed Up Mermaid and Bruised Violet, $6.71, or create your own color combo.

For a quick pop of color, Kahlani recommends using hair chalk on braids. "Plait the hair, then put the chalk on top of a few sections and set with hairspray," she says.

Who it works on: Light blondes, ashy blondes and golden brunettes can easily copy Ora's deep blue and purple look. But if your hair is darker, you can still get the dip-dye effect, explains Kahlani, by going for deeper reds and pinks like Bleach London's I Saw Red and The Big Pink.

Yes, her lavender shade was pastel perfection, but her current dark blue is much subtler -- ideal if you're thinking about transitioning colored hair into your everyday look. Plus, you can tint the hair without having to bleach your whole head first.

Try this: Manic Panic Semi-Permanent Hair Color in After Midnight, $13.99, is our go-to match for Richie's look, but it's designed to last several weeks. "You can use dishwashing soap if you've got to get it out quickly for work," Kahlani says of getting the dye to fade faster if you find yourself in a pinch. "Cleansing shampoos and just washing it a lot will help, too."

Who it works on: Lighter hair colors will get a more vibrant blue, whereas dark hair will get a dark tint.

"I'm in the process of going through the entire rainbow," Kesha said in a recent interview. And true to her word, she's since been spotted with shades of lavender and baby blue this summer.

Try this: To get Kesha's light pink shade you don't have to worry about coating every strand perfectly -- it's more of a highlighted look. Divide the hair into sections as you roughly spray on a pale color like Bumble and Bumble Spray Chalk in Blush, $19, throughout the hair.

Who it works on: If you have your heart set on the cotton candy pink or light lavender shades, and your hair is naturally dark, you'll have to go to the salon first to lighten your hair. The process of going that light can be ultra-damaging, so don't try to do it at home, Kahlani cautions.

But if going blond for the sake of pink strands is not on your wish list, try picking up some stencils from your local craft store. "Those show up great on dark hair," says Kahlani.