Hikers should not underestimate the risks of climbing in Japan during the volatile spring transition in May, a mountaineering expert has warned after two Hong Kong men became stranded in the Northern Alps, one of whom later died.

Veteran mountaineer Chung Kin-man said on Wednesday that climbers might develop a false sense of safety due to warmer weather in lowland areas in May, even as conditions in the mountains remained unstable, with risks of snowstorms, strong winds and freezing temperatures.

He said May falls between the traditional winter and summer climbing seasons, creating highly unstable conditions that required mountaineers to prepare for both cold and wet environments.

“May is not a stable period for climbing; it’s not completely warm and there may still be cold spells,” Chung said.

“In hotter conditions, you would normally bring much less gear, wear fewer clothes and use different equipment, and even your climbing schedule would be different.

“But if you use warm-weather gear in May, it may not be enough. Strong winds or snowstorms can sometimes arrive suddenly, and you may not have sufficient protection to keep your body warm enough to withstand the conditions.”