The sister of a missing 21-year-old woman is appealing for the public to help find her.

Kim Bambus was last seen in Ponsonby yesterday morning when she told her friends she was going for a run at Piha.

Her car has been found on Log Race Road, in Piha, at the entrance to the Ahuahu Track.

Kim's sister Storm Bambus says Kim was wearing a dark coloured jacket, pink exercise top, black shorts and black and white Nike exercise shoes.

Storm says the police need the public's help.

"We just need any kind of information," she said. "If anyone has seen her or been at the walking tracks any time yesterday, we just need to know."