This NASA Earth Observatory image obtained on October 21, 2017, shows a natural-color image of Typhoon Lan in the western Pacific on October 20, 2017. Photo: AFP / NASA Earth Observatory / Handout.

Tens of thousands of people were advised to evacuate, hundreds of flights were cancelled and rail services disrupted as heavy rain and wind lashed a wide swathe of Japan on Sunday, a national election day, as a powerful typhoon neared.

Typhoon Lan, classified as an intense Category 4 storm by the Tropical Storm Risk monitoring site, was south of Japan and moving northeast at 40 kph on Sunday afternoon, the Japan Meteorological Agency said.

An agency official told a news conference that while the storm appeared to have weakened slightly from its peak, it was still a powerful storm that could pound parts of Japan with more than 80 mm (3 inches) of rain an hour and might make landfall near Tokyo early on Monday.

“It will make landfall as a strong typhoon,” he added.

The agency issued warnings for heavy rain and flooding on the Pacific side of Japan including the Tokyo metropolitan area, even though the typhoon is likely to be downgraded to Category 3 by Sunday evening, with the activity of a seasonal rain front intensified by the storm.

More than 20,000 households in various parts of Japan were advised to evacuate, NHK public television said, though there were no immediate reports of damage or injuries.

Japanese Prime Minister Shinzo Abe said he had called on the government to take steps as early as possible to minimise any threats to people’s lives.

Media reported the grounding of flights and interrupted rail services in southern and western parts of the country. Wind and rain were intensifying in Tokyo.

The bad weather could hinder voter turnout in the general election, where Prime Minister Shinzo Abe’s Liberal Democratic Party-led (LDP) coalition is on track to roughly match the two-thirds “super majority” it held in parliament’s lower house before dissolution.

Divisions in the opposition camp and jitters over North Korea’s nuclear and missile programmes are likely to help the ruling coalition, media forecasts have said.

Authorities in Okinawa moved the voting date to Saturday for some remote islands as the storm neared.