Two US students trapped in the New Zealand wilderness by a snowstorm trekked back out to safety after surviving their nine-day ordeal by rationing their meager supplies of trail mix and warming themselves in hot springs.

Alec Brown and Erica Klintworth, both 21, returned to the city of Christchurch on Monday after meeting up with members of a search team - famished but otherwise in good shape, police said.

The two students, on a foreign study program in New Zealand with University of Wisconsin, had planned to hike and camp for a few days at some hot springs on the country's South Island. But heavy rains and a snowstorm prevented the couple from being able to cross a river and return.

"Unfortunately it rained and rained, day after day, and snowed," Alec Brown wrote in an email to The Associated Press on Monday.