A plan to use snow collected in Japan's mountains to cool 2020 Olympics venues this summer is being hindered by snowfalls on track to be the lowest on record, according to officials.

Authorities in Minami-Uonuma in Niigata prefecture north of Tokyo have been trying to collect and store snow to bring by train to Olympic football and basketball venues. The project is costing about $490,000.

However, a mild winter lacking adequate snowfall that cannot even blanket popular ski resorts may cause authorities to shelve their plans.

With temperatures around Tokyo often rising to 40 degrees Celsius (104 degrees Fahrenheit) in the summer, organisers are also planning to use mist sprays and water stations to refresh spectators.

At ski resorts around the country, snow depths are well below average and higher temperatures mean any white stuff that falls melts away quickly, forcing some areas to bring it in by truck.

"It is the first time in 30 years that there hasn't been enough snow ... You can't even ski down to the bottom," said Yoshihiro Tsuchiya, a hotel owner in Hakuba.

This winter is the warmest on record, according to the Japan Meteorological Agency.

Japan's warm weather is part of a wider pattern of climatic change caused by human carbon emissions, Professor Michael Mann, director of the Earth System Science Centre at Pennsylvania State University, said.

Maximum snow depths in areas along the Sea of Japan decreased by as much as 15 percent per decade in the years between 1962 and 2016, according to a ministry of environment study in 2018.