A 63-year-old Invercargill woman who spent Monday night missing in the north of the city has been found safe, police say.

Police had asked for the public's help on Monday evening to find Mary Coakley, who has dementia and was described as vulnerable. She was last seen on Durham Street in Waikiwi on Monday 2 November.

By Tuesday morning the search had widened across the Waikiwi area, with Land Search and Rescue volunteers working alongside police. Later that morning police said she had been located on semi-rural farmland on the outskirts of the city.

Police said she was "in good spirits" and was being given medical attention. They thanked the members of the public who checked their properties and the LandSAR volunteers who turned out.

In the appeal issued on Monday night, police said they thought the woman may have sought shelter somewhere overnight, and asked anyone living around Durham Street and the wider Waikiwi area to look through sheds, garages and gardens. They described her as about 160cm tall with short blonde-grey hair and a fringe, and said she was thought to be dressed in grey track pants and a black hoodie, with pink laces in her black shoes.

Waikiwi sits at the northern edge of Invercargill, where the city's streets give way to lifestyle blocks and farm paddocks, so a person on foot can move quite quickly from suburban roads into open country. Police have not said exactly where she was found.

Police treat a missing person with dementia as urgent because of the risk of a night in the open, and Tuesday's result, with the woman found within about a day of being reported missing, is the outcome searchers work for. The appeal relied heavily on residents being willing to look around their own properties, and police said that help, along with LandSAR's, made the difference.

If someone with dementia goes missing, police ask that families call 111 straight away rather than waiting, as early reports give searchers the best chance of a quick find.