Alec Brown and Erica Klintworth, both 21, were reported missing Saturday after they failed to return to their flat in Christchurch by Wednesday, New Zealand's Fairfax News reported.
The couple, both students at Canterbury University in Wisconsin, were hiking near Arthur's Pass when they got caught in a snowstorm.
They had planned on being back between Monday and Wednesday, but became stranded when they were unable to cross a swollen river.
They survived the temperatures, which got down to 17.6 F, by regularly getting into nearby natural hot pools.
West Coast search and rescue leader Sean Judd said the area the couple got stranded in luckily was not hit by the worst of the storm. If it had, and the hot springs had not been there, the pair would probably have died, Judd said.
"[It's] not a bad way to lift your spirits when you're stuck in the hills in the miserable cold weather," Judd said.
The couple admittedly were unprepared for their trek, but when they were finally located by rescuers, they were in "pretty good" condition, Judd said.
"They were OK; a little bit hungry, as you can imagine. They'd been rationing their food for a few days," Judd said.