The Duchess, her husband Prince William and their son Prince George arrived in Wellington just after midday on Monday to wild weather and the enthusiastic cheers of a small group of supporters.

When they touched down it was 15 degrees and blowing a gale. Kate, who was holding eight-month-old baby George as she exited the plane, struggled to contain her hair, dress and hat.

Still, she managed to maintain a smile.

And, despite the gloomy weather, Catherine lit up the grey skies, looking regal in red.

"Oh lovely, she looks gorgeous doesn't she?" gushed one onlooker, of her red knee-length coat and maroon pillbox hat.

The dress and coat was designed by Catherine Walker, a British designer favoured by Princess Diana. The Duchess' hat was by Gina Foster.

She also wore a brooch given to her by Queen Elizabeth, Fairfaz NZ reports. The Queen herself was given the brooch during her 1953-54 tour of New Zealand.

It was a change of outfit from the grey tweed coat she wore when she touched down in Sydney this morning, en route to New Zealand.

George, who was wearing a navy jumpsuit when the royal family landed in Sydney, also dressed up for the first official stop of their tour.

One onlooker, Edna Hurd, broke into the national anthem as the royals drove past the crowd.

"I just think it's great," Hurd said. "Kate looks lovely in her red, even in this weather."

But, she was concerned about baby George's bald head.

"I do wish he had been wearing a hat in this cold," she said.

He was dressed in cream while dad William wore a navy suit with a maroon tie.

The young royal family is at the start of a three-week trip around New Zealand and Australia, their first official tour as a family.

For this tour, the Duke and Duchess and their son will be accompanied by an entourage of 12, including a nanny for Prince George and a hairdresser for the Duchess. With weather like this, she'll no doubt need it.