Nevertheless, Neill Glover plans to take a 600km fundraising ride through Death Valley National Park, from Yosemite to Las Vegas, in the United States.
It would be symbolic of the battles people waged against cancer, he said.
Mr Glover said Death Valley held the record for the highest reliably reported temperature in the western hemisphere.
In 1913, temperatures rose to a sweltering 56.7degC at Furnace Creek - just short of the world record which was 58degC in Al Aziziyah, Libya in 1922.
He hoped to begin his four-day adventure across the barren terrain next April.
He will ride a mountain bike because the road surface will be a mixture of tar seal and gravel.
He has begun training, doing rides around the city wearing three pairs of thermals, a couple of jerseys and a hat to increase his body temperature.
Soon, he will also begin training at the University of Otago School of Physical Education's heat chamber, where the heat can be increased and the atmosphere made dry like the desert conditions in Death Valley.
"I'll build up the length of rides in the heat over the next six months so it won't be a shock when I get there," Mr Glover said.
He will also wear special compression clothing which will stop the atmosphere sucking the moisture out of his body.
Mr Glover said he would take a support crew of about 12 people, some of whom would ride with him, while others would drive campervans for the crew to sleep in at night.
He plans to do two 75km rides each day - one in the morning and one in the evening, with a "nap" in between - to avoid riding in the hottest part of the day.
The ride would be a huge challenge, he said.
"I might be in my late 50s, but I'm not past it by any means."
The project was inspired by his son's battle with cancer.
Thirty years ago, he was diagnosed with leukaemia and Mr Glover could only sit and watch him fight the cancer.
"Ultimately, he beat it and went on to become a healthy father of his own two fabulous children."
For this reason, Mr Glover hopes his ride will raise up to $1 million for the Child Cancer Foundation.
He will use social networking websites to spread the word about his ride.
"Almost everyone knows at least 10 people. If I ask the 10 people I know to donate $1 each, and ask 10 people they know to do the same, it would only need six levels to get to 1 million people."
