Plans to use snow to keep fans cool at Tokyo 2020 are under threat due to a shortage of supplies.
Organisers had intended to use both real and fake snow as part of their efforts to combat the expected high temperatures in the Japanese capital.
It was hoped that snow would be transported from the Minamiuonuma ski resort in Japan's central Niigata Prefecture but there has been a record shortage.
Milder temperatures mean that Japan has witnessed its "worst snow season in decades", Kyodo News reported.
A snow storage facility at Minamiuonuma can hold up to 1,600 tonnes of snow but is said to contain only a few centimetres.
More than 100 tonnes is thought to be required to make the Tokyo 2020 plan viable, the same as 10 large trucks.
Snow was going to be taken to the capital by rail and road and then stored at the Games in tents.
"Personal snow packs" could then be handed out to fans at venues.
The shortage has severely impacted resorts which have been hit by a decline in visitor numbers.
Large amounts of snow are not expected "any time soon", with the annual Minami Uonuma Snow Festival among the events cancelled.
"I don't ever recall experiencing a no-snow winter like this one," said Mutsumi Seki, a Minamiuonuma city employee who is in charge of the snow storage facility, to Kyodo News.
"We welcome any amount of snow, but we don't need any more rain."
Heat is a major concern for Tokyo 2020 officials as more than 50 deaths were recorded in Japan because of rising temperatures in July last year.
The Olympic Games are scheduled for between July 24 and August 9.
Other heat prevention measures which will be used include cooling mist sprays and shading tents.
Fans could be allowed to bring their own bottled water into venues under certain conditions, which is normally against the rules.
Snow machines have already been trialled at Tokyo 2020 test events.
The fears over the heat have prompted organisers to controversially switch the marathons and race walking to Sapporo, more than 800 kilometres to the north of Tokyo.
Other events have been given earlier start times.