Households and businesses in the Tokyo area on Saturday began a period of power conservation, spanning from July to August, as the electricity supply is forecast to become tight in the area this summer.

Photo taken March 22, 2022, shows the head office of Tokyo Electric Power Company Holdings Inc. in Tokyo. (Kyodo)

The Japanese government has issued a request based on the projection that the reserve power capacity rate in the region served by Tokyo Electric Power Company Holdings Inc. in July could drop to 3.1 percent, slightly above the lowest level for maintaining a stable supply, if a once-in-a-decade level of extreme heat grips the area.

Since electricity demand could swing about 3 percent from the anticipated level, it is necessary to secure at least a 3 percent reserve, according to the Ministry of Economy, Trade and Industry.

The rate is projected to improve to 4.8 percent in the TEPCO-serving region in August, while that in other regions is expected to stay above 5 percent in July and August, a ministry official said.

Last year, the government issued a nationwide power-saving request from July to September, but the latest request only targets the area served by TEPCO.

Last summer's request was the first issued since fiscal 2015 when all of the country's nuclear reactors were offline in the wake of the Fukushima nuclear power plant disaster in 2011.

The country's weather agency has predicted Japan may face a hotter summer due to the influence of the El Nino climate pattern -- warmer water in the central and eastern Pacific -- among other reasons.

Besides the nation's capital, TEPCO serves Kanagawa, Saitama, Chiba, Tochigi, Gunma, Ibaraki, Yamanashi and part of Shizuoka prefectures, according to the utility.