Missing woman, 84, found alive in WA park

An elderly woman has been found weak but alive days after she went missing in a national park in Western Australia.

Patricia Byrne, 84, was found on Sunday after last being seen on Thursday morning in the Stirling Range National Park which sparked a land and air search effort of Mount Trio.

Ms Byrne has been "weakened from the incident" but was able to speak with her rescuers.

Her medical condition is still being assessed, police say.

She has been taken to Albany Health Campus for treatment.

It's understood she had no food or water with her during the ordeal.

Grandson Blair Coatsworth said it was "awesome news" after fearing she was dead.

"The police officer walked over to us and we thought we were getting the worst of the worst and then he just hit us with the best lotto win," he told reporters.

"She's probably the hardest 84-year-old you'd know. She would take on a gang of people that woman and to hear she came out the way she did was sort of what you'd expect from her."

WA Police sergeant Allan Mallard found Ms Byrne walking along the side of the road about four kilometres away from where she was last spotted.

"It was a bit of a shock to be fair. I was like 'stop, stop the car', and tried to jump out of the car while it was still moving," he told the Nine Network.

More than 40 State Emergency Service volunteers, WA police, park ranges and the tracker dog team had combed the area since Thursday before she was found.