Colour the hot trend at cool Melbourne Cup

It might have been the coolest Melbourne Cup in more than a decade, but the temperature didn't stop Flemington's fashionistas from bringing some heat.

International supermodel Lara Stone was shivering, but on-trend in a yellow lace custom-made Alex Perry dress.

"I thought it was supposed to be spring here," she told reporters.

Jetting into Australia as a guest of the Victoria Racing Club and Emirates, Stone said she was thrilled to be at Flemington, although initially didn't know what she was coming for.

"When I first heard about the Melbourne Cup, embarrassingly enough I thought it was tennis," she said

"It took me a couple of weeks to realise how important it is and how excited everyone here is ... it's infectious."

Also donning Alex Perry was Jennifer Hawkins, although the face of Myer sensibly popped a coat over her black and cream look.

"I called a jacket in last minute, it's just too cold," she told AAP.

Although bucking the colour trend, Hawkins backed brightness as the day's fashion favourite.

And sure enough, famous faces including TV personalities Rebecca Judd, Jodi Anasta, Lauren Phillips and former Cup-winning jockey Michelle Payne attended in various shades of pink.

Even the opposition leader's wife, Chloe Shorten, rocked a fuchsia jacket and red fascinator by Melbourne-based milliner Murley and Co.

"I feel like I've already won walking around with Chloe," said federal Labor leader Bill Shorten, wearing a matching red polka dot tie.

Yellow was also a popular choice, with model Samantha Harris, Bachelor star Anna Heinrich and footy WAG Kylie Brown all donning the shade.

But it was rock star royalty, Paris Jackson, who stole the show in a rust-coloured Morrison dress and crystal Ann Stonebridge headpiece.

The daughter of the late Michael Jackson was due to wear a red custom-made Alex Perry dress to attend her first Melbourne Cup, but ditched it at the last minute for the more bohemian number and tan boots.

"This is one of the first times where I get to fully express myself," she told the Seven Network of her outfit.

"I know it's a big headwear (event) so they let me wear quartz in my head."

On her first trip to Australia, Jackson posed for photos outside the Myer marquee.

"I was hoping maybe some sunshine would be here but the sunshine is coming from the people," she added.

Among the general admission crowd, it took ruffles, stripes, lace and more colour for Tasmanian Holly Sternes to take out the Melbourne Cup best-dressed at Myer Fashions on the Field.

She impressed the judges in a loose-fitting, nude-tone dress with bright yellow embellishments by Nicola Finetti, paired with a dramatic pastel-pink headpiece with bows and flowers.

"I feel pretty blown away being from Tasmania. I decided to enter a week ago," Ms Sternes told reporters.

"I saw this ... dress and I just couldn't walk past it. I had to have it."

Away from the warmth of the invite-only marquees, jackets were popular as punters prepared for the coldest Cup weather in more than a decade, with the temperature reaching a top of 16C in Melbourne on Tuesday.