Palmerston woman Hannah Hutcheson, whose 10-year-old daughter Sophie has the condition, said her sister Chelsey Johnston suggested the daily hike to the Sir John McKenzie monument- dubbed "31 Climbs in 31 Days''.
"I think some days will be a bit slow, but we'll get there,'' she said.
The sisters will be joined in their endeavour by their husbands, Matt Hutcheson and Aaron Johnston, with proceeds from their fundraising going to Breath4CF Otago.
It was crucial people with the condition got enough exercise, Mrs Hutcheson said.
Despite Sophie's condition she was an active child, and Mrs Hutcheson said she hoped her daughter would climb to the monument as well, at least some of the time.
"We encourage her to participate in as many sports and physical activities as possible.''
Mrs Johnston said the family was "very close'' and they were looking forward to the challenge, but due to work and other demands on their time the four expected to be completing it at different times during the day.
Cystic fibrosis primarily affects the lungs, but also the pancreas, liver, kidneys, and intestine. It can cause recurrent lung infections, sinus infections and poor growth among other issues.
It was a daily battle to keep up with all Sophie's medication, which included at least 20 pills a day, Mrs Hutcheson said.
She also needed a diet high in calories and salt, and her medical needs included outpatient appointments every three months for lung function tests.
The two couples have already launched their Facebook and Givealittle pages, "31 climbs in 31 days'' to fundraise.
