Tokyo: Japan's weather agency on Monday urged people to exercise caution as heavy snow is forecast to hit mainly northern to western areas along the Sea of Japan through Tuesday.

In the six hours through 6 a.m. local time on Monday, snowfall reached about 20 cm in Hirakawa City in Aomori Prefecture, Minamiaizu Town in Fukushima Prefecture, and Minakami Town in Gunma Prefecture, according to the Japan Meteorological Agency (JMA).

In the 24 hours through Tuesday morning, up to 60 cm of snowfall is forecast in the Hokuriku region and 50 cm in Hokkaido and the Tohoku and Kanto-Koshin regions due to a powerful winter pressure pattern, the JMA said.

Weather officials urged people, primarily in northern through western regions along the Sea of Japan, to be vigilant against avalanches and snow accumulation on electric wires and trees, reports Xinhua news agency.

Earlier on December 19, the first snowfall of the season fell in central Tokyo, 15 days earlier than an average year and 25 days earlier than last season, the country's weather agency said.

The temperature measured 3.3 degrees Celsius in the Japanese capital at 7 a.m. local time on Thursday, shortly after snow was confirmed to be falling in Minato Ward, Tokyo, according to the Japan Meteorological Agency.

The season's first snowfall was also observed in other locations of the Kanto region, including Yokohama and Kumagaya, Saitama Prefecture, from Wednesday night to dawn on Thursday, the JMA said.

Weather officials warned of heavy snowfall over the mountainous areas in western and southwestern regions of Japan.

Heavy snowfall has accumulated in some regions, prompting authorities to warn drivers to use winter tyres and stay updated on weather conditions. The beginning of the winter often sees a spike in accidents due to inexperience with snowy roads.