The government called on households and businesses in Tokyo and surrounding areas to reduce their electricity usage Monday and will ask the same for Tuesday due to heightened demand as Japan braces for a lengthy and hot summer after an early end to the rainy season.

The industry ministry issued its first-ever power supply advisory a day earlier, urging people in Tokyo Electric Power Company Holdings Inc.'s service area to take energy-saving steps between 3 p.m. and 6 p.m. Monday, such as turning off lights that are not in use.

People wearing masks walk outside JR Tokyo Station amid high temperatures on June 27, 2022. (Kyodo)

As the capital braces for potential shortages of increasingly expensive energy, Japan's weather agency announced Monday that the rainy season in Tokyo and neighboring areas appears to have ended, marking the shortest season since data became available in 1951.

An increase in solar power output and electricity-saving efforts are believed to have helped ease the situation beyond expectations Monday, averting a power crunch for the day.

The power supply advisory is issued when an area's reserve power supply capacity ratio is projected to fall below 5 percent. The lowest level necessary for stable supply is said to be 3 percent.

The government will call for households and businesses to reduce electricity usage again between 3 p.m. and 6 p.m. Tuesday, with reserve rates forecast to be tightest between 4 p.m. and 5 p.m., at 3.9 percent.

But, despite the calls for power saving, the Ministry of Economy, Trade and Industry is still urging the continued and appropriate use of air conditioners due to the heightened risk of heatstroke.

The interior of Japan's Economy, Trade and Industry Ministry building in Tokyo is dimly lit on June 27, 2022, as the ministry called on households and businesses in Tokyo and surrounding areas to reduce their electricity usage. (Kyodo)

TEPCO's service area covers Tokyo and eight nearby prefectures, including those in eastern Japan's Kanto region, which endured record-high June temperatures over the weekend. Numerous regions in the service area also saw temperatures of 35 C or higher Monday, with Sano in Tochigi Prefecture recording the highest, at 39.8 C.

Other major electricity suppliers across Japan, including Tohoku Electric Power Co., which serves the country's northeast and central Japan's Chubu Electric Power Co., are expected to see significant demand this summer.

Reserve rates in July are projected to be 3.1 percent in the Tohoku, Tokyo and Chubu areas and 3.8 percent in regions, including western and southwestern Japan.

The ministry's system for power usage advisories was introduced following a review into the response to high demand in March this year when a powerful earthquake in the country's northeast region caused some power plants to halt operations.

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Rainy season ends in Tokyo, neighboring areas, earliest since 1951

Mercury climbs to 40.2 C in Japan, national record for June