Temperatures at the snow-covered peak of Mt Taranaki could fall as low as -13°C tonight as rescuers search for a climber who has been missing more than 24 hours.
Police were alerted around 3.50pm today that the man had failed to return from yesterday's climbing trip.
He was expected back on Tuesday evening.
Police and Search and Rescue teams will stay on the mountain till midnight tonight, and searchers will reassess tomorrow morning.
Fairfax reported the person had summitted the mountain but failed to return.
The search was focusing on tracks near the top of the mountain, which is 2,518m above sea level.
The Taranaki Rescue Helicopter has been helping the ground teams with the search.
A car was reportedly found this afternoon at the North Egmont carpark, where the main climbing route to the summit starts.
MetService said the temperature at the summit was -13°C at 6am today, with wind chill taken into account, and would have been -12°C at 6pm this evening.
Lower down the mountain, near the North Egmont Visitor Centre, the temperature is around 2°C.
The trek from the carpark to the summit is considered a reasonable climb for experienced hikers, although conditions can be difficult in winter.
Taranaki Alpine Club president Elaine Sinton said the climber would have been well equipped if they were attempting to climb the summit at this time of year.
Tracks near the summit of the mountain would be covered in snow and would require serious climbing equipment, including crampons and ice picks, Sinton said.