The soaring mercury in Japan comes as North America, Europe and other parts of Asia experience hot conditions this week, taxing power grids and raising the prospect of spiking energy prices across three continents.
Beijing saw highs of 40°C on Tuesday, and parts of China including Hebei province are forecast to breach that level on Wednesday, according to the China Meteorological Administration.
Driving Japan’s prolonged heat wave is a high-pressure system extending west from the Pacific, which is trapping heat close to the surface, said Takahisa Nishikawa, lead meteorologist for Japan at The Weather Company.
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Known as the Pacific high, this area of high atmospheric pressure is stronger than normal for this time of year as a result of warm sea-surface temperatures, he added.
On Monday, Japan’s nationwide next-day power prices jumped around 25% to a 15-week high. The rise in demand for cooling is stretching a grid that’s already under pressure from ongoing power plant maintenance.
Bringing some temporary relief from the heat is Tropical Depression Sepat, which is approaching Japan from the south and is expected to weaken as it nears Tokyo. The storm, along with a stationary frontal system, is triggering cloudy and rainy conditions and lowering maximum daytime temperatures, said James Caron, director of meteorological operations for North America and Asia at Atmospheric G2.
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The cloudy conditions will temporarily help moderate temperatures, but they also lead to warmer nights and lower solar power output. “Cloud cover acts like an insulating blanket at night, trapping heat that the Earth’s surface radiates after sunset,” Caron said.
By next week, another wave of uncomfortably high temperatures is predicted to sweep across Japan, as an elongated high-pressure system — known as a ridge — sits over the country. “As one ridge departs, another seems to take its place, leading to a prolonged heat wave,” said Tucker Bradley, a meteorologist at Vaisala.
With electricity supplies already tight, consecutive days of high temperatures next week could cause power prices to spike, said Yu Koyanagi, an energy trader at MFT Energy.
The heat wave could stretch beyond early July. Weather models are forecasting the possibility of another tropical storm developing south of Japan in the week starting July 7, although its path is still uncertain.
If the storm tracks toward Taiwan and China, it can draw warm and humid air from the tropics toward Japan, bringing another round of heightened temperatures, Caron said.
Chart: Bloomberg
