Kathmandu: A Spanish climber on Tuesday abandoned his bid to make the first winter ascent of Mount Everest in 25 years after “lethal weather” forced him to retreat.

It is the second time in as many years that mountaineer Alex Txikon, 36, has been forced to call off his attempt to scale the world’s highest peak in winter without the use of tanked oxygen.

The last successful winter summit was in 1993 by a Japanese team. But only one climber has previously reached the peak in winter without using supplemental oxygen: a Nepali mountaineer in December 1987.

“Alex has ended his expedition. He reached up to Camp Four but the weather did not favour him,” Mingma Sherpa of Seven Summit Treks, which managed the logistics of Txikon’s Everest bid, said.

Txikon and his team reached 7,950 metres at the weekend, roughly 900 metres below the summit.

Weather forecasts had indicated that strong winds would calm early Sunday, allowing them to press on to the summit.

But winds up to 100 kilometres per hour forced the team, which included experienced Pakistani climber Mohammad Ali Sadpara, to return to base camp.

“We are back at base camp from C4 (Camp Four). Very strong winds and lethal weather made it almost impossible to go for the summit,” Sadpara posted on Facebook.

The temperatures near the summit of Everest in winter regularly plunge below minus 40 Celsius while the wind chill makes it feel even colder.

In those conditions exposed skin freezes in less than five minutes, putting climbers at serious risk of frostbite.

Limited oxygen at high altitudes also increases the risk of frostbite as the body directs oxygen-rich blood toward its core and away from extremities.

Txikon was climbing without supplemental oxygen used by many climbers to reduce the effects of Everest’s extreme altitudes.

The five Nepali Sherpa guides climbing with the Spaniard were used tanked oxygen. It is not clear if Sadpara was too.

In 2016 Txikon and Sadpara became the first climbers to summit Pakistan’s Nanga Parbat (8,125 metres) — nicknamed the “Killer Mountain” — in winter, a feat they achieved without using additional oxygen.

Hundreds of climbers flock to Everest each year hoping to reach the top of the world. But most attempt it during a narrow window of calm weather between late April and May.

Mountaineering is a major revenue-earner for impoverished Nepal, which is home to eight of the world’s 14 peaks over 8,000 metres.